http://git-wip-us.apache.org/repos/asf/hbase/blob/cb77a925/src/main/asciidoc/_chapters/hbase-default.adoc ---------------------------------------------------------------------- diff --git a/src/main/asciidoc/_chapters/hbase-default.adoc b/src/main/asciidoc/_chapters/hbase-default.adoc new file mode 100644 index 0000000..23b96d5 --- /dev/null +++ b/src/main/asciidoc/_chapters/hbase-default.adoc @@ -0,0 +1,2254 @@ + + + +//// +/** + * + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +//// + +:doctype: book +:numbered: +:toc: left +:icons: font +:experimental: + +[[hbase_default_configurations]] +=== HBase Default Configuration + +The documentation below is generated using the default hbase configuration file, _hbase-default.xml_, as source. + + +[[hbase.tmp.dir]] +*`hbase.tmp.dir`*:: ++ +.Description +Temporary directory on the local filesystem. + Change this setting to point to a location more permanent + than '/tmp', the usual resolve for java.io.tmpdir, as the + '/tmp' directory is cleared on machine restart. ++ +.Default +`${java.io.tmpdir}/hbase-${user.name}` + + +[[hbase.rootdir]] +*`hbase.rootdir`*:: ++ +.Description +The directory shared by region servers and into + which HBase persists. The URL should be 'fully-qualified' + to include the filesystem scheme. For example, to specify the + HDFS directory '/hbase' where the HDFS instance's namenode is + running at namenode.example.org on port 9000, set this value to: + hdfs://namenode.example.org:9000/hbase. By default, we write + to whatever ${hbase.tmp.dir} is set too -- usually /tmp -- + so change this configuration or else all data will be lost on + machine restart. ++ +.Default +`${hbase.tmp.dir}/hbase` + + +[[hbase.cluster.distributed]] +*`hbase.cluster.distributed`*:: ++ +.Description +The mode the cluster will be in. Possible values are + false for standalone mode and true for distributed mode. If + false, startup will run all HBase and ZooKeeper daemons together + in the one JVM. ++ +.Default +`false` + + +[[hbase.zookeeper.quorum]] +*`hbase.zookeeper.quorum`*:: ++ +.Description +Comma separated list of servers in the ZooKeeper ensemble + (This config. should have been named hbase.zookeeper.ensemble). + For example, "host1.mydomain.com,host2.mydomain.com,host3.mydomain.com". + By default this is set to localhost for local and pseudo-distributed modes + of operation. For a fully-distributed setup, this should be set to a full + list of ZooKeeper ensemble servers. If HBASE_MANAGES_ZK is set in hbase-env.sh + this is the list of servers which hbase will start/stop ZooKeeper on as + part of cluster start/stop. Client-side, we will take this list of + ensemble members and put it together with the hbase.zookeeper.clientPort + config. and pass it into zookeeper constructor as the connectString + parameter. ++ +.Default +`localhost` + + +[[hbase.local.dir]] +*`hbase.local.dir`*:: ++ +.Description +Directory on the local filesystem to be used + as a local storage. ++ +.Default +`${hbase.tmp.dir}/local/` + + +[[hbase.master.info.port]] +*`hbase.master.info.port`*:: ++ +.Description +The port for the HBase Master web UI. + Set to -1 if you do not want a UI instance run. ++ +.Default +`16010` + + +[[hbase.master.info.bindAddress]] +*`hbase.master.info.bindAddress`*:: ++ +.Description +The bind address for the HBase Master web UI + ++ +.Default +`0.0.0.0` + + +[[hbase.master.logcleaner.plugins]] +*`hbase.master.logcleaner.plugins`*:: ++ +.Description +A comma-separated list of BaseLogCleanerDelegate invoked by + the LogsCleaner service. These WAL cleaners are called in order, + so put the cleaner that prunes the most files in front. To + implement your own BaseLogCleanerDelegate, just put it in HBase's classpath + and add the fully qualified class name here. Always add the above + default log cleaners in the list. ++ +.Default +`org.apache.hadoop.hbase.master.cleaner.TimeToLiveLogCleaner` + + +[[hbase.master.logcleaner.ttl]] +*`hbase.master.logcleaner.ttl`*:: ++ +.Description +Maximum time a WAL can stay in the .oldlogdir directory, + after which it will be cleaned by a Master thread. ++ +.Default +`600000` + + +[[hbase.master.hfilecleaner.plugins]] +*`hbase.master.hfilecleaner.plugins`*:: ++ +.Description +A comma-separated list of BaseHFileCleanerDelegate invoked by + the HFileCleaner service. These HFiles cleaners are called in order, + so put the cleaner that prunes the most files in front. To + implement your own BaseHFileCleanerDelegate, just put it in HBase's classpath + and add the fully qualified class name here. Always add the above + default log cleaners in the list as they will be overwritten in + hbase-site.xml. ++ +.Default +`org.apache.hadoop.hbase.master.cleaner.TimeToLiveHFileCleaner` + + +[[hbase.master.catalog.timeout]] +*`hbase.master.catalog.timeout`*:: ++ +.Description +Timeout value for the Catalog Janitor from the master to + META. ++ +.Default +`600000` + + +[[hbase.master.infoserver.redirect]] +*`hbase.master.infoserver.redirect`*:: ++ +.Description +Whether or not the Master listens to the Master web + UI port (hbase.master.info.port) and redirects requests to the web + UI server shared by the Master and RegionServer. ++ +.Default +`true` + + +[[hbase.regionserver.port]] +*`hbase.regionserver.port`*:: ++ +.Description +The port the HBase RegionServer binds to. ++ +.Default +`16020` + + +[[hbase.regionserver.info.port]] +*`hbase.regionserver.info.port`*:: ++ +.Description +The port for the HBase RegionServer web UI + Set to -1 if you do not want the RegionServer UI to run. ++ +.Default +`16030` + + +[[hbase.regionserver.info.bindAddress]] +*`hbase.regionserver.info.bindAddress`*:: ++ +.Description +The address for the HBase RegionServer web UI ++ +.Default +`0.0.0.0` + + +[[hbase.regionserver.info.port.auto]] +*`hbase.regionserver.info.port.auto`*:: ++ +.Description +Whether or not the Master or RegionServer + UI should search for a port to bind to. Enables automatic port + search if hbase.regionserver.info.port is already in use. + Useful for testing, turned off by default. ++ +.Default +`false` + + +[[hbase.regionserver.handler.count]] +*`hbase.regionserver.handler.count`*:: ++ +.Description +Count of RPC Listener instances spun up on RegionServers. + Same property is used by the Master for count of master handlers. ++ +.Default +`30` + + +[[hbase.ipc.server.callqueue.handler.factor]] +*`hbase.ipc.server.callqueue.handler.factor`*:: ++ +.Description +Factor to determine the number of call queues. + A value of 0 means a single queue shared between all the handlers. + A value of 1 means that each handler has its own queue. ++ +.Default +`0.1` + + +[[hbase.ipc.server.callqueue.read.ratio]] +*`hbase.ipc.server.callqueue.read.ratio`*:: ++ +.Description +Split the call queues into read and write queues. + The specified interval (which should be between 0.0 and 1.0) + will be multiplied by the number of call queues. + A value of 0 indicate to not split the call queues, meaning that both read and write + requests will be pushed to the same set of queues. + A value lower than 0.5 means that there will be less read queues than write queues. + A value of 0.5 means there will be the same number of read and write queues. + A value greater than 0.5 means that there will be more read queues than write queues. + A value of 1.0 means that all the queues except one are used to dispatch read requests. + + Example: Given the total number of call queues being 10 + a read.ratio of 0 means that: the 10 queues will contain both read/write requests. + a read.ratio of 0.3 means that: 3 queues will contain only read requests + and 7 queues will contain only write requests. + a read.ratio of 0.5 means that: 5 queues will contain only read requests + and 5 queues will contain only write requests. + a read.ratio of 0.8 means that: 8 queues will contain only read requests + and 2 queues will contain only write requests. + a read.ratio of 1 means that: 9 queues will contain only read requests + and 1 queues will contain only write requests. + ++ +.Default +`0` + + +[[hbase.ipc.server.callqueue.scan.ratio]] +*`hbase.ipc.server.callqueue.scan.ratio`*:: ++ +.Description +Given the number of read call queues, calculated from the total number + of call queues multiplied by the callqueue.read.ratio, the scan.ratio property + will split the read call queues into small-read and long-read queues. + A value lower than 0.5 means that there will be less long-read queues than short-read queues. + A value of 0.5 means that there will be the same number of short-read and long-read queues. + A value greater than 0.5 means that there will be more long-read queues than short-read queues + A value of 0 or 1 indicate to use the same set of queues for gets and scans. + + Example: Given the total number of read call queues being 8 + a scan.ratio of 0 or 1 means that: 8 queues will contain both long and short read requests. + a scan.ratio of 0.3 means that: 2 queues will contain only long-read requests + and 6 queues will contain only short-read requests. + a scan.ratio of 0.5 means that: 4 queues will contain only long-read requests + and 4 queues will contain only short-read requests. + a scan.ratio of 0.8 means that: 6 queues will contain only long-read requests + and 2 queues will contain only short-read requests. + ++ +.Default +`0` + + +[[hbase.regionserver.msginterval]] +*`hbase.regionserver.msginterval`*:: ++ +.Description +Interval between messages from the RegionServer to Master + in milliseconds. ++ +.Default +`3000` + + +[[hbase.regionserver.regionSplitLimit]] +*`hbase.regionserver.regionSplitLimit`*:: ++ +.Description +Limit for the number of regions after which no more region + splitting should take place. This is not a hard limit for the number of + regions but acts as a guideline for the regionserver to stop splitting after + a certain limit. Default is MAX_INT; i.e. do not block splitting. ++ +.Default +`2147483647` + + +[[hbase.regionserver.logroll.period]] +*`hbase.regionserver.logroll.period`*:: ++ +.Description +Period at which we will roll the commit log regardless + of how many edits it has. ++ +.Default +`3600000` + + +[[hbase.regionserver.logroll.errors.tolerated]] +*`hbase.regionserver.logroll.errors.tolerated`*:: ++ +.Description +The number of consecutive WAL close errors we will allow + before triggering a server abort. A setting of 0 will cause the + region server to abort if closing the current WAL writer fails during + log rolling. Even a small value (2 or 3) will allow a region server + to ride over transient HDFS errors. ++ +.Default +`2` + + +[[hbase.regionserver.hlog.reader.impl]] +*`hbase.regionserver.hlog.reader.impl`*:: ++ +.Description +The WAL file reader implementation. ++ +.Default +`org.apache.hadoop.hbase.regionserver.wal.ProtobufLogReader` + + +[[hbase.regionserver.hlog.writer.impl]] +*`hbase.regionserver.hlog.writer.impl`*:: ++ +.Description +The WAL file writer implementation. ++ +.Default +`org.apache.hadoop.hbase.regionserver.wal.ProtobufLogWriter` + + +[[hbase.master.distributed.log.replay]] +*`hbase.master.distributed.log.replay`*:: ++ +.Description +Enable 'distributed log replay' as default engine splitting + WAL files on server crash. This default is new in hbase 1.0. To fall + back to the old mode 'distributed log splitter', set the value to + 'false'. 'Disributed log replay' improves MTTR because it does not + write intermediate files. 'DLR' required that 'hfile.format.version' + be set to version 3 or higher. + ++ +.Default +`true` + + +[[hbase.regionserver.global.memstore.size]] +*`hbase.regionserver.global.memstore.size`*:: ++ +.Description +Maximum size of all memstores in a region server before new + updates are blocked and flushes are forced. Defaults to 40% of heap. + Updates are blocked and flushes are forced until size of all memstores + in a region server hits hbase.regionserver.global.memstore.size.lower.limit. ++ +.Default +`0.4` + + +[[hbase.regionserver.global.memstore.size.lower.limit]] +*`hbase.regionserver.global.memstore.size.lower.limit`*:: ++ +.Description +Maximum size of all memstores in a region server before flushes are forced. + Defaults to 95% of hbase.regionserver.global.memstore.size. + A 100% value for this value causes the minimum possible flushing to occur when updates are + blocked due to memstore limiting. ++ +.Default +`0.95` + + +[[hbase.regionserver.optionalcacheflushinterval]] +*`hbase.regionserver.optionalcacheflushinterval`*:: ++ +.Description + + Maximum amount of time an edit lives in memory before being automatically flushed. + Default 1 hour. Set it to 0 to disable automatic flushing. ++ +.Default +`3600000` + + +[[hbase.regionserver.catalog.timeout]] +*`hbase.regionserver.catalog.timeout`*:: ++ +.Description +Timeout value for the Catalog Janitor from the regionserver to META. ++ +.Default +`600000` + + +[[hbase.regionserver.dns.interface]] +*`hbase.regionserver.dns.interface`*:: ++ +.Description +The name of the Network Interface from which a region server + should report its IP address. ++ +.Default +`default` + + +[[hbase.regionserver.dns.nameserver]] +*`hbase.regionserver.dns.nameserver`*:: ++ +.Description +The host name or IP address of the name server (DNS) + which a region server should use to determine the host name used by the + master for communication and display purposes. ++ +.Default +`default` + + +[[hbase.regionserver.region.split.policy]] +*`hbase.regionserver.region.split.policy`*:: ++ +.Description + + A split policy determines when a region should be split. The various other split policies that + are available currently are ConstantSizeRegionSplitPolicy, DisabledRegionSplitPolicy, + DelimitedKeyPrefixRegionSplitPolicy, KeyPrefixRegionSplitPolicy etc. + ++ +.Default +`org.apache.hadoop.hbase.regionserver.IncreasingToUpperBoundRegionSplitPolicy` + + +[[zookeeper.session.timeout]] +*`zookeeper.session.timeout`*:: ++ +.Description +ZooKeeper session timeout in milliseconds. It is used in two different ways. + First, this value is used in the ZK client that HBase uses to connect to the ensemble. + It is also used by HBase when it starts a ZK server and it is passed as the 'maxSessionTimeout'. See + http://hadoop.apache.org/zookeeper/docs/current/zookeeperProgrammers.html#ch_zkSessions. + For example, if a HBase region server connects to a ZK ensemble that's also managed by HBase, then the + session timeout will be the one specified by this configuration. But, a region server that connects + to an ensemble managed with a different configuration will be subjected that ensemble's maxSessionTimeout. So, + even though HBase might propose using 90 seconds, the ensemble can have a max timeout lower than this and + it will take precedence. The current default that ZK ships with is 40 seconds, which is lower than HBase's. + ++ +.Default +`90000` + + +[[zookeeper.znode.parent]] +*`zookeeper.znode.parent`*:: ++ +.Description +Root ZNode for HBase in ZooKeeper. All of HBase's ZooKeeper + files that are configured with a relative path will go under this node. + By default, all of HBase's ZooKeeper file path are configured with a + relative path, so they will all go under this directory unless changed. ++ +.Default +`/hbase` + + +[[zookeeper.znode.rootserver]] +*`zookeeper.znode.rootserver`*:: ++ +.Description +Path to ZNode holding root region location. This is written by + the master and read by clients and region servers. If a relative path is + given, the parent folder will be ${zookeeper.znode.parent}. By default, + this means the root location is stored at /hbase/root-region-server. ++ +.Default +`root-region-server` + + +[[zookeeper.znode.acl.parent]] +*`zookeeper.znode.acl.parent`*:: ++ +.Description +Root ZNode for access control lists. ++ +.Default +`acl` + + +[[hbase.zookeeper.dns.interface]] +*`hbase.zookeeper.dns.interface`*:: ++ +.Description +The name of the Network Interface from which a ZooKeeper server + should report its IP address. ++ +.Default +`default` + + +[[hbase.zookeeper.dns.nameserver]] +*`hbase.zookeeper.dns.nameserver`*:: ++ +.Description +The host name or IP address of the name server (DNS) + which a ZooKeeper server should use to determine the host name used by the + master for communication and display purposes. ++ +.Default +`default` + + +[[hbase.zookeeper.peerport]] +*`hbase.zookeeper.peerport`*:: ++ +.Description +Port used by ZooKeeper peers to talk to each other. + See http://hadoop.apache.org/zookeeper/docs/r3.1.1/zookeeperStarted.html#sc_RunningReplicatedZooKeeper + for more information. ++ +.Default +`2888` + + +[[hbase.zookeeper.leaderport]] +*`hbase.zookeeper.leaderport`*:: ++ +.Description +Port used by ZooKeeper for leader election. + See http://hadoop.apache.org/zookeeper/docs/r3.1.1/zookeeperStarted.html#sc_RunningReplicatedZooKeeper + for more information. ++ +.Default +`3888` + + +[[hbase.zookeeper.useMulti]] +*`hbase.zookeeper.useMulti`*:: ++ +.Description +Instructs HBase to make use of ZooKeeper's multi-update functionality. + This allows certain ZooKeeper operations to complete more quickly and prevents some issues + with rare Replication failure scenarios (see the release note of HBASE-2611 for an example). + IMPORTANT: only set this to true if all ZooKeeper servers in the cluster are on version 3.4+ + and will not be downgraded. ZooKeeper versions before 3.4 do not support multi-update and + will not fail gracefully if multi-update is invoked (see ZOOKEEPER-1495). ++ +.Default +`true` + + +[[hbase.config.read.zookeeper.config]] +*`hbase.config.read.zookeeper.config`*:: ++ +.Description + + Set to true to allow HBaseConfiguration to read the + zoo.cfg file for ZooKeeper properties. Switching this to true + is not recommended, since the functionality of reading ZK + properties from a zoo.cfg file has been deprecated. ++ +.Default +`false` + + +[[hbase.zookeeper.property.initLimit]] +*`hbase.zookeeper.property.initLimit`*:: ++ +.Description +Property from ZooKeeper's config zoo.cfg. + The number of ticks that the initial synchronization phase can take. ++ +.Default +`10` + + +[[hbase.zookeeper.property.syncLimit]] +*`hbase.zookeeper.property.syncLimit`*:: ++ +.Description +Property from ZooKeeper's config zoo.cfg. + The number of ticks that can pass between sending a request and getting an + acknowledgment. ++ +.Default +`5` + + +[[hbase.zookeeper.property.dataDir]] +*`hbase.zookeeper.property.dataDir`*:: ++ +.Description +Property from ZooKeeper's config zoo.cfg. + The directory where the snapshot is stored. ++ +.Default +`${hbase.tmp.dir}/zookeeper` + + +[[hbase.zookeeper.property.clientPort]] +*`hbase.zookeeper.property.clientPort`*:: ++ +.Description +Property from ZooKeeper's config zoo.cfg. + The port at which the clients will connect. ++ +.Default +`2181` + + +[[hbase.zookeeper.property.maxClientCnxns]] +*`hbase.zookeeper.property.maxClientCnxns`*:: ++ +.Description +Property from ZooKeeper's config zoo.cfg. + Limit on number of concurrent connections (at the socket level) that a + single client, identified by IP address, may make to a single member of + the ZooKeeper ensemble. Set high to avoid zk connection issues running + standalone and pseudo-distributed. ++ +.Default +`300` + + +[[hbase.client.write.buffer]] +*`hbase.client.write.buffer`*:: ++ +.Description +Default size of the HTable client write buffer in bytes. + A bigger buffer takes more memory -- on both the client and server + side since server instantiates the passed write buffer to process + it -- but a larger buffer size reduces the number of RPCs made. + For an estimate of server-side memory-used, evaluate + hbase.client.write.buffer * hbase.regionserver.handler.count ++ +.Default +`2097152` + + +[[hbase.client.pause]] +*`hbase.client.pause`*:: ++ +.Description +General client pause value. Used mostly as value to wait + before running a retry of a failed get, region lookup, etc. + See hbase.client.retries.number for description of how we backoff from + this initial pause amount and how this pause works w/ retries. ++ +.Default +`100` + + +[[hbase.client.retries.number]] +*`hbase.client.retries.number`*:: ++ +.Description +Maximum retries. Used as maximum for all retryable + operations such as the getting of a cell's value, starting a row update, + etc. Retry interval is a rough function based on hbase.client.pause. At + first we retry at this interval but then with backoff, we pretty quickly reach + retrying every ten seconds. See HConstants#RETRY_BACKOFF for how the backup + ramps up. Change this setting and hbase.client.pause to suit your workload. ++ +.Default +`35` + + +[[hbase.client.max.total.tasks]] +*`hbase.client.max.total.tasks`*:: ++ +.Description +The maximum number of concurrent tasks a single HTable instance will + send to the cluster. ++ +.Default +`100` + + +[[hbase.client.max.perserver.tasks]] +*`hbase.client.max.perserver.tasks`*:: ++ +.Description +The maximum number of concurrent tasks a single HTable instance will + send to a single region server. ++ +.Default +`5` + + +[[hbase.client.max.perregion.tasks]] +*`hbase.client.max.perregion.tasks`*:: ++ +.Description +The maximum number of concurrent connections the client will + maintain to a single Region. That is, if there is already + hbase.client.max.perregion.tasks writes in progress for this region, new puts + won't be sent to this region until some writes finishes. ++ +.Default +`1` + + +[[hbase.client.scanner.caching]] +*`hbase.client.scanner.caching`*:: ++ +.Description +Number of rows that will be fetched when calling next + on a scanner if it is not served from (local, client) memory. Higher + caching values will enable faster scanners but will eat up more memory + and some calls of next may take longer and longer times when the cache is empty. + Do not set this value such that the time between invocations is greater + than the scanner timeout; i.e. hbase.client.scanner.timeout.period ++ +.Default +`100` + + +[[hbase.client.keyvalue.maxsize]] +*`hbase.client.keyvalue.maxsize`*:: ++ +.Description +Specifies the combined maximum allowed size of a KeyValue + instance. This is to set an upper boundary for a single entry saved in a + storage file. Since they cannot be split it helps avoiding that a region + cannot be split any further because the data is too large. It seems wise + to set this to a fraction of the maximum region size. Setting it to zero + or less disables the check. ++ +.Default +`10485760` + + +[[hbase.client.scanner.timeout.period]] +*`hbase.client.scanner.timeout.period`*:: ++ +.Description +Client scanner lease period in milliseconds. ++ +.Default +`60000` + + +[[hbase.client.localityCheck.threadPoolSize]] +*`hbase.client.localityCheck.threadPoolSize`*:: ++ +.Description + ++ +.Default +`2` + + +[[hbase.bulkload.retries.number]] +*`hbase.bulkload.retries.number`*:: ++ +.Description +Maximum retries. This is maximum number of iterations + to atomic bulk loads are attempted in the face of splitting operations + 0 means never give up. ++ +.Default +`10` + + +[[hbase.balancer.period + ]] +*`hbase.balancer.period + `*:: ++ +.Description +Period at which the region balancer runs in the Master. ++ +.Default +`300000` + + +[[hbase.regions.slop]] +*`hbase.regions.slop`*:: ++ +.Description +Rebalance if any regionserver has average + (average * slop) regions. ++ +.Default +`0.2` + + +[[hbase.server.thread.wakefrequency]] +*`hbase.server.thread.wakefrequency`*:: ++ +.Description +Time to sleep in between searches for work (in milliseconds). + Used as sleep interval by service threads such as log roller. ++ +.Default +`10000` + + +[[hbase.server.versionfile.writeattempts]] +*`hbase.server.versionfile.writeattempts`*:: ++ +.Description + + How many time to retry attempting to write a version file + before just aborting. Each attempt is seperated by the + hbase.server.thread.wakefrequency milliseconds. ++ +.Default +`3` + + +[[hbase.hregion.memstore.flush.size]] +*`hbase.hregion.memstore.flush.size`*:: ++ +.Description + + Memstore will be flushed to disk if size of the memstore + exceeds this number of bytes. Value is checked by a thread that runs + every hbase.server.thread.wakefrequency. ++ +.Default +`134217728` + + +[[hbase.hregion.percolumnfamilyflush.size.lower.bound]] +*`hbase.hregion.percolumnfamilyflush.size.lower.bound`*:: ++ +.Description + + If FlushLargeStoresPolicy is used, then every time that we hit the + total memstore limit, we find out all the column families whose memstores + exceed this value, and only flush them, while retaining the others whose + memstores are lower than this limit. If none of the families have their + memstore size more than this, all the memstores will be flushed + (just as usual). This value should be less than half of the total memstore + threshold (hbase.hregion.memstore.flush.size). + ++ +.Default +`16777216` + + +[[hbase.hregion.preclose.flush.size]] +*`hbase.hregion.preclose.flush.size`*:: ++ +.Description + + If the memstores in a region are this size or larger when we go + to close, run a "pre-flush" to clear out memstores before we put up + the region closed flag and take the region offline. On close, + a flush is run under the close flag to empty memory. During + this time the region is offline and we are not taking on any writes. + If the memstore content is large, this flush could take a long time to + complete. The preflush is meant to clean out the bulk of the memstore + before putting up the close flag and taking the region offline so the + flush that runs under the close flag has little to do. ++ +.Default +`5242880` + + +[[hbase.hregion.memstore.block.multiplier]] +*`hbase.hregion.memstore.block.multiplier`*:: ++ +.Description + + Block updates if memstore has hbase.hregion.memstore.block.multiplier + times hbase.hregion.memstore.flush.size bytes. Useful preventing + runaway memstore during spikes in update traffic. Without an + upper-bound, memstore fills such that when it flushes the + resultant flush files take a long time to compact or split, or + worse, we OOME. ++ +.Default +`4` + + +[[hbase.hregion.memstore.mslab.enabled]] +*`hbase.hregion.memstore.mslab.enabled`*:: ++ +.Description + + Enables the MemStore-Local Allocation Buffer, + a feature which works to prevent heap fragmentation under + heavy write loads. This can reduce the frequency of stop-the-world + GC pauses on large heaps. ++ +.Default +`true` + + +[[hbase.hregion.max.filesize]] +*`hbase.hregion.max.filesize`*:: ++ +.Description + + Maximum HFile size. If the sum of the sizes of a region's HFiles has grown to exceed this + value, the region is split in two. ++ +.Default +`10737418240` + + +[[hbase.hregion.majorcompaction]] +*`hbase.hregion.majorcompaction`*:: ++ +.Description +Time between major compactions, expressed in milliseconds. Set to 0 to disable + time-based automatic major compactions. User-requested and size-based major compactions will + still run. This value is multiplied by hbase.hregion.majorcompaction.jitter to cause + compaction to start at a somewhat-random time during a given window of time. The default value + is 7 days, expressed in milliseconds. If major compactions are causing disruption in your + environment, you can configure them to run at off-peak times for your deployment, or disable + time-based major compactions by setting this parameter to 0, and run major compactions in a + cron job or by another external mechanism. ++ +.Default +`604800000` + + +[[hbase.hregion.majorcompaction.jitter]] +*`hbase.hregion.majorcompaction.jitter`*:: ++ +.Description +A multiplier applied to hbase.hregion.majorcompaction to cause compaction to occur + a given amount of time either side of hbase.hregion.majorcompaction. The smaller the number, + the closer the compactions will happen to the hbase.hregion.majorcompaction + interval. ++ +.Default +`0.50` + + +[[hbase.hstore.compactionThreshold]] +*`hbase.hstore.compactionThreshold`*:: ++ +.Description + If more than this number of StoreFiles exist in any one Store + (one StoreFile is written per flush of MemStore), a compaction is run to rewrite all + StoreFiles into a single StoreFile. Larger values delay compaction, but when compaction does + occur, it takes longer to complete. ++ +.Default +`3` + + +[[hbase.hstore.flusher.count]] +*`hbase.hstore.flusher.count`*:: ++ +.Description + The number of flush threads. With fewer threads, the MemStore flushes will be + queued. With more threads, the flushes will be executed in parallel, increasing the load on + HDFS, and potentially causing more compactions. ++ +.Default +`2` + + +[[hbase.hstore.blockingStoreFiles]] +*`hbase.hstore.blockingStoreFiles`*:: ++ +.Description + If more than this number of StoreFiles exist in any one Store (one StoreFile + is written per flush of MemStore), updates are blocked for this region until a compaction is + completed, or until hbase.hstore.blockingWaitTime has been exceeded. ++ +.Default +`10` + + +[[hbase.hstore.blockingWaitTime]] +*`hbase.hstore.blockingWaitTime`*:: ++ +.Description + The time for which a region will block updates after reaching the StoreFile limit + defined by hbase.hstore.blockingStoreFiles. After this time has elapsed, the region will stop + blocking updates even if a compaction has not been completed. ++ +.Default +`90000` + + +[[hbase.hstore.compaction.min]] +*`hbase.hstore.compaction.min`*:: ++ +.Description +The minimum number of StoreFiles which must be eligible for compaction before + compaction can run. The goal of tuning hbase.hstore.compaction.min is to avoid ending up with + too many tiny StoreFiles to compact. Setting this value to 2 would cause a minor compaction + each time you have two StoreFiles in a Store, and this is probably not appropriate. If you + set this value too high, all the other values will need to be adjusted accordingly. For most + cases, the default value is appropriate. In previous versions of HBase, the parameter + hbase.hstore.compaction.min was named hbase.hstore.compactionThreshold. ++ +.Default +`3` + + +[[hbase.hstore.compaction.max]] +*`hbase.hstore.compaction.max`*:: ++ +.Description +The maximum number of StoreFiles which will be selected for a single minor + compaction, regardless of the number of eligible StoreFiles. Effectively, the value of + hbase.hstore.compaction.max controls the length of time it takes a single compaction to + complete. Setting it larger means that more StoreFiles are included in a compaction. For most + cases, the default value is appropriate. ++ +.Default +`10` + + +[[hbase.hstore.compaction.min.size]] +*`hbase.hstore.compaction.min.size`*:: ++ +.Description +A StoreFile smaller than this size will always be eligible for minor compaction. + HFiles this size or larger are evaluated by hbase.hstore.compaction.ratio to determine if + they are eligible. Because this limit represents the "automatic include"limit for all + StoreFiles smaller than this value, this value may need to be reduced in write-heavy + environments where many StoreFiles in the 1-2 MB range are being flushed, because every + StoreFile will be targeted for compaction and the resulting StoreFiles may still be under the + minimum size and require further compaction. If this parameter is lowered, the ratio check is + triggered more quickly. This addressed some issues seen in earlier versions of HBase but + changing this parameter is no longer necessary in most situations. Default: 128 MB expressed + in bytes. ++ +.Default +`134217728` + + +[[hbase.hstore.compaction.max.size]] +*`hbase.hstore.compaction.max.size`*:: ++ +.Description +A StoreFile larger than this size will be excluded from compaction. The effect of + raising hbase.hstore.compaction.max.size is fewer, larger StoreFiles that do not get + compacted often. If you feel that compaction is happening too often without much benefit, you + can try raising this value. Default: the value of LONG.MAX_VALUE, expressed in bytes. ++ +.Default +`9223372036854775807` + + +[[hbase.hstore.compaction.ratio]] +*`hbase.hstore.compaction.ratio`*:: ++ +.Description +For minor compaction, this ratio is used to determine whether a given StoreFile + which is larger than hbase.hstore.compaction.min.size is eligible for compaction. Its + effect is to limit compaction of large StoreFiles. The value of hbase.hstore.compaction.ratio + is expressed as a floating-point decimal. A large ratio, such as 10, will produce a single + giant StoreFile. Conversely, a low value, such as .25, will produce behavior similar to the + BigTable compaction algorithm, producing four StoreFiles. A moderate value of between 1.0 and + 1.4 is recommended. When tuning this value, you are balancing write costs with read costs. + Raising the value (to something like 1.4) will have more write costs, because you will + compact larger StoreFiles. However, during reads, HBase will need to seek through fewer + StoreFiles to accomplish the read. Consider this approach if you cannot take advantage of + Bloom filters. Otherwise, you can lower this value to something like 1.0 to reduce the + background cost of writes, and use Bloom filters to control the number of StoreFiles touched + during reads. For most cases, the default value is appropriate. ++ +.Default +`1.2F` + + +[[hbase.hstore.compaction.ratio.offpeak]] +*`hbase.hstore.compaction.ratio.offpeak`*:: ++ +.Description +Allows you to set a different (by default, more aggressive) ratio for determining + whether larger StoreFiles are included in compactions during off-peak hours. Works in the + same way as hbase.hstore.compaction.ratio. Only applies if hbase.offpeak.start.hour and + hbase.offpeak.end.hour are also enabled. ++ +.Default +`5.0F` + + +[[hbase.hstore.time.to.purge.deletes]] +*`hbase.hstore.time.to.purge.deletes`*:: ++ +.Description +The amount of time to delay purging of delete markers with future timestamps. If + unset, or set to 0, all delete markers, including those with future timestamps, are purged + during the next major compaction. Otherwise, a delete marker is kept until the major compaction + which occurs after the marker's timestamp plus the value of this setting, in milliseconds. + ++ +.Default +`0` + + +[[hbase.offpeak.start.hour]] +*`hbase.offpeak.start.hour`*:: ++ +.Description +The start of off-peak hours, expressed as an integer between 0 and 23, inclusive. + Set to -1 to disable off-peak. ++ +.Default +`-1` + + +[[hbase.offpeak.end.hour]] +*`hbase.offpeak.end.hour`*:: ++ +.Description +The end of off-peak hours, expressed as an integer between 0 and 23, inclusive. Set + to -1 to disable off-peak. ++ +.Default +`-1` + + +[[hbase.regionserver.thread.compaction.throttle]] +*`hbase.regionserver.thread.compaction.throttle`*:: ++ +.Description +There are two different thread pools for compactions, one for large compactions and + the other for small compactions. This helps to keep compaction of lean tables (such as + hbase:meta) fast. If a compaction is larger than this threshold, it + goes into the large compaction pool. In most cases, the default value is appropriate. Default: + 2 x hbase.hstore.compaction.max x hbase.hregion.memstore.flush.size (which defaults to 128MB). + The value field assumes that the value of hbase.hregion.memstore.flush.size is unchanged from + the default. ++ +.Default +`2684354560` + + +[[hbase.hstore.compaction.kv.max]] +*`hbase.hstore.compaction.kv.max`*:: ++ +.Description +The maximum number of KeyValues to read and then write in a batch when flushing or + compacting. Set this lower if you have big KeyValues and problems with Out Of Memory + Exceptions Set this higher if you have wide, small rows. ++ +.Default +`10` + + +[[hbase.storescanner.parallel.seek.enable]] +*`hbase.storescanner.parallel.seek.enable`*:: ++ +.Description + + Enables StoreFileScanner parallel-seeking in StoreScanner, + a feature which can reduce response latency under special conditions. ++ +.Default +`false` + + +[[hbase.storescanner.parallel.seek.threads]] +*`hbase.storescanner.parallel.seek.threads`*:: ++ +.Description + + The default thread pool size if parallel-seeking feature enabled. ++ +.Default +`10` + + +[[hfile.block.cache.size]] +*`hfile.block.cache.size`*:: ++ +.Description +Percentage of maximum heap (-Xmx setting) to allocate to block cache + used by a StoreFile. Default of 0.4 means allocate 40%. + Set to 0 to disable but it's not recommended; you need at least + enough cache to hold the storefile indices. ++ +.Default +`0.4` + + +[[hfile.block.index.cacheonwrite]] +*`hfile.block.index.cacheonwrite`*:: ++ +.Description +This allows to put non-root multi-level index blocks into the block + cache at the time the index is being written. ++ +.Default +`false` + + +[[hfile.index.block.max.size]] +*`hfile.index.block.max.size`*:: ++ +.Description +When the size of a leaf-level, intermediate-level, or root-level + index block in a multi-level block index grows to this size, the + block is written out and a new block is started. ++ +.Default +`131072` + + +[[hbase.bucketcache.ioengine]] +*`hbase.bucketcache.ioengine`*:: ++ +.Description +Where to store the contents of the bucketcache. One of: onheap, + offheap, or file. If a file, set it to file:PATH_TO_FILE. See https://hbase.apache.org/apidocs/org/apache/hadoop/hbase/io/hfile/CacheConfig.html for more information. + ++ +.Default +`` + + +[[hbase.bucketcache.combinedcache.enabled]] +*`hbase.bucketcache.combinedcache.enabled`*:: ++ +.Description +Whether or not the bucketcache is used in league with the LRU + on-heap block cache. In this mode, indices and blooms are kept in the LRU + blockcache and the data blocks are kept in the bucketcache. ++ +.Default +`true` + + +[[hbase.bucketcache.size]] +*`hbase.bucketcache.size`*:: ++ +.Description +The size of the buckets for the bucketcache if you only use a single size. + Defaults to the default blocksize, which is 64 * 1024. ++ +.Default +`65536` + + +[[hbase.bucketcache.sizes]] +*`hbase.bucketcache.sizes`*:: ++ +.Description +A comma-separated list of sizes for buckets for the bucketcache + if you use multiple sizes. Should be a list of block sizes in order from smallest + to largest. The sizes you use will depend on your data access patterns. ++ +.Default +`` + + +[[hfile.format.version]] +*`hfile.format.version`*:: ++ +.Description +The HFile format version to use for new files. + Version 3 adds support for tags in hfiles (See http://hbase.apache.org/book.html#hbase.tags). + Distributed Log Replay requires that tags are enabled. Also see the configuration + 'hbase.replication.rpc.codec'. + ++ +.Default +`3` + + +[[hfile.block.bloom.cacheonwrite]] +*`hfile.block.bloom.cacheonwrite`*:: ++ +.Description +Enables cache-on-write for inline blocks of a compound Bloom filter. ++ +.Default +`false` + + +[[io.storefile.bloom.block.size]] +*`io.storefile.bloom.block.size`*:: ++ +.Description +The size in bytes of a single block ("chunk") of a compound Bloom + filter. This size is approximate, because Bloom blocks can only be + inserted at data block boundaries, and the number of keys per data + block varies. ++ +.Default +`131072` + + +[[hbase.rs.cacheblocksonwrite]] +*`hbase.rs.cacheblocksonwrite`*:: ++ +.Description +Whether an HFile block should be added to the block cache when the + block is finished. ++ +.Default +`false` + + +[[hbase.rpc.timeout]] +*`hbase.rpc.timeout`*:: ++ +.Description +This is for the RPC layer to define how long HBase client applications + take for a remote call to time out. It uses pings to check connections + but will eventually throw a TimeoutException. ++ +.Default +`60000` + + +[[hbase.rpc.shortoperation.timeout]] +*`hbase.rpc.shortoperation.timeout`*:: ++ +.Description +This is another version of "hbase.rpc.timeout". For those RPC operation + within cluster, we rely on this configuration to set a short timeout limitation + for short operation. For example, short rpc timeout for region server's trying + to report to active master can benefit quicker master failover process. ++ +.Default +`10000` + + +[[hbase.ipc.client.tcpnodelay]] +*`hbase.ipc.client.tcpnodelay`*:: ++ +.Description +Set no delay on rpc socket connections. See + http://docs.oracle.com/javase/1.5.0/docs/api/java/net/Socket.html#getTcpNoDelay() ++ +.Default +`true` + + +[[hbase.master.keytab.file]] +*`hbase.master.keytab.file`*:: ++ +.Description +Full path to the kerberos keytab file to use for logging in + the configured HMaster server principal. ++ +.Default +`` + + +[[hbase.master.kerberos.principal]] +*`hbase.master.kerberos.principal`*:: ++ +.Description +Ex. "hbase/_h...@example.com". The kerberos principal name + that should be used to run the HMaster process. The principal name should + be in the form: user/hostname@DOMAIN. If "_HOST" is used as the hostname + portion, it will be replaced with the actual hostname of the running + instance. ++ +.Default +`` + + +[[hbase.regionserver.keytab.file]] +*`hbase.regionserver.keytab.file`*:: ++ +.Description +Full path to the kerberos keytab file to use for logging in + the configured HRegionServer server principal. ++ +.Default +`` + + +[[hbase.regionserver.kerberos.principal]] +*`hbase.regionserver.kerberos.principal`*:: ++ +.Description +Ex. "hbase/_h...@example.com". The kerberos principal name + that should be used to run the HRegionServer process. The principal name + should be in the form: user/hostname@DOMAIN. If "_HOST" is used as the + hostname portion, it will be replaced with the actual hostname of the + running instance. An entry for this principal must exist in the file + specified in hbase.regionserver.keytab.file ++ +.Default +`` + + +[[hadoop.policy.file]] +*`hadoop.policy.file`*:: ++ +.Description +The policy configuration file used by RPC servers to make + authorization decisions on client requests. Only used when HBase + security is enabled. ++ +.Default +`hbase-policy.xml` + + +[[hbase.superuser]] +*`hbase.superuser`*:: ++ +.Description +List of users or groups (comma-separated), who are allowed + full privileges, regardless of stored ACLs, across the cluster. + Only used when HBase security is enabled. ++ +.Default +`` + + +[[hbase.auth.key.update.interval]] +*`hbase.auth.key.update.interval`*:: ++ +.Description +The update interval for master key for authentication tokens + in servers in milliseconds. Only used when HBase security is enabled. ++ +.Default +`86400000` + + +[[hbase.auth.token.max.lifetime]] +*`hbase.auth.token.max.lifetime`*:: ++ +.Description +The maximum lifetime in milliseconds after which an + authentication token expires. Only used when HBase security is enabled. ++ +.Default +`604800000` + + +[[hbase.ipc.client.fallback-to-simple-auth-allowed]] +*`hbase.ipc.client.fallback-to-simple-auth-allowed`*:: ++ +.Description +When a client is configured to attempt a secure connection, but attempts to + connect to an insecure server, that server may instruct the client to + switch to SASL SIMPLE (unsecure) authentication. This setting controls + whether or not the client will accept this instruction from the server. + When false (the default), the client will not allow the fallback to SIMPLE + authentication, and will abort the connection. ++ +.Default +`false` + + +[[hbase.display.keys]] +*`hbase.display.keys`*:: ++ +.Description +When this is set to true the webUI and such will display all start/end keys + as part of the table details, region names, etc. When this is set to false, + the keys are hidden. ++ +.Default +`true` + + +[[hbase.coprocessor.region.classes]] +*`hbase.coprocessor.region.classes`*:: ++ +.Description +A comma-separated list of Coprocessors that are loaded by + default on all tables. For any override coprocessor method, these classes + will be called in order. After implementing your own Coprocessor, just put + it in HBase's classpath and add the fully qualified class name here. + A coprocessor can also be loaded on demand by setting HTableDescriptor. ++ +.Default +`` + + +[[hbase.rest.port]] +*`hbase.rest.port`*:: ++ +.Description +The port for the HBase REST server. ++ +.Default +`8080` + + +[[hbase.rest.readonly]] +*`hbase.rest.readonly`*:: ++ +.Description +Defines the mode the REST server will be started in. Possible values are: + false: All HTTP methods are permitted - GET/PUT/POST/DELETE. + true: Only the GET method is permitted. ++ +.Default +`false` + + +[[hbase.rest.threads.max]] +*`hbase.rest.threads.max`*:: ++ +.Description +The maximum number of threads of the REST server thread pool. + Threads in the pool are reused to process REST requests. This + controls the maximum number of requests processed concurrently. + It may help to control the memory used by the REST server to + avoid OOM issues. If the thread pool is full, incoming requests + will be queued up and wait for some free threads. ++ +.Default +`100` + + +[[hbase.rest.threads.min]] +*`hbase.rest.threads.min`*:: ++ +.Description +The minimum number of threads of the REST server thread pool. + The thread pool always has at least these number of threads so + the REST server is ready to serve incoming requests. ++ +.Default +`2` + + +[[hbase.rest.support.proxyuser]] +*`hbase.rest.support.proxyuser`*:: ++ +.Description +Enables running the REST server to support proxy-user mode. ++ +.Default +`false` + + +[[hbase.defaults.for.version.skip]] +*`hbase.defaults.for.version.skip`*:: ++ +.Description +Set to true to skip the 'hbase.defaults.for.version' check. + Setting this to true can be useful in contexts other than + the other side of a maven generation; i.e. running in an + ide. You'll want to set this boolean to true to avoid + seeing the RuntimException complaint: "hbase-default.xml file + seems to be for and old version of HBase (\${hbase.version}), this + version is X.X.X-SNAPSHOT" ++ +.Default +`false` + + +[[hbase.coprocessor.master.classes]] +*`hbase.coprocessor.master.classes`*:: ++ +.Description +A comma-separated list of + org.apache.hadoop.hbase.coprocessor.MasterObserver coprocessors that are + loaded by default on the active HMaster process. For any implemented + coprocessor methods, the listed classes will be called in order. After + implementing your own MasterObserver, just put it in HBase's classpath + and add the fully qualified class name here. ++ +.Default +`` + + +[[hbase.coprocessor.abortonerror]] +*`hbase.coprocessor.abortonerror`*:: ++ +.Description +Set to true to cause the hosting server (master or regionserver) + to abort if a coprocessor fails to load, fails to initialize, or throws an + unexpected Throwable object. Setting this to false will allow the server to + continue execution but the system wide state of the coprocessor in question + will become inconsistent as it will be properly executing in only a subset + of servers, so this is most useful for debugging only. ++ +.Default +`true` + + +[[hbase.online.schema.update.enable]] +*`hbase.online.schema.update.enable`*:: ++ +.Description +Set true to enable online schema changes. ++ +.Default +`true` + + +[[hbase.table.lock.enable]] +*`hbase.table.lock.enable`*:: ++ +.Description +Set to true to enable locking the table in zookeeper for schema change operations. + Table locking from master prevents concurrent schema modifications to corrupt table + state. ++ +.Default +`true` + + +[[hbase.table.max.rowsize]] +*`hbase.table.max.rowsize`*:: ++ +.Description + + Maximum size of single row in bytes (default is 1 Gb) for Get'ting + or Scan'ning without in-row scan flag set. If row size exceeds this limit + RowTooBigException is thrown to client. + ++ +.Default +`1073741824` + + +[[hbase.thrift.minWorkerThreads]] +*`hbase.thrift.minWorkerThreads`*:: ++ +.Description +The "core size" of the thread pool. New threads are created on every + connection until this many threads are created. ++ +.Default +`16` + + +[[hbase.thrift.maxWorkerThreads]] +*`hbase.thrift.maxWorkerThreads`*:: ++ +.Description +The maximum size of the thread pool. When the pending request queue + overflows, new threads are created until their number reaches this number. + After that, the server starts dropping connections. ++ +.Default +`1000` + + +[[hbase.thrift.maxQueuedRequests]] +*`hbase.thrift.maxQueuedRequests`*:: ++ +.Description +The maximum number of pending Thrift connections waiting in the queue. If + there are no idle threads in the pool, the server queues requests. Only + when the queue overflows, new threads are added, up to + hbase.thrift.maxQueuedRequests threads. ++ +.Default +`1000` + + +[[hbase.thrift.htablepool.size.max]] +*`hbase.thrift.htablepool.size.max`*:: ++ +.Description +The upper bound for the table pool used in the Thrift gateways server. + Since this is per table name, we assume a single table and so with 1000 default + worker threads max this is set to a matching number. For other workloads this number + can be adjusted as needed. + ++ +.Default +`1000` + + +[[hbase.regionserver.thrift.framed]] +*`hbase.regionserver.thrift.framed`*:: ++ +.Description +Use Thrift TFramedTransport on the server side. + This is the recommended transport for thrift servers and requires a similar setting + on the client side. Changing this to false will select the default transport, + vulnerable to DoS when malformed requests are issued due to THRIFT-601. + ++ +.Default +`false` + + +[[hbase.regionserver.thrift.framed.max_frame_size_in_mb]] +*`hbase.regionserver.thrift.framed.max_frame_size_in_mb`*:: ++ +.Description +Default frame size when using framed transport ++ +.Default +`2` + + +[[hbase.regionserver.thrift.compact]] +*`hbase.regionserver.thrift.compact`*:: ++ +.Description +Use Thrift TCompactProtocol binary serialization protocol. ++ +.Default +`false` + + +[[hbase.data.umask.enable]] +*`hbase.data.umask.enable`*:: ++ +.Description +Enable, if true, that file permissions should be assigned + to the files written by the regionserver ++ +.Default +`false` + + +[[hbase.data.umask]] +*`hbase.data.umask`*:: ++ +.Description +File permissions that should be used to write data + files when hbase.data.umask.enable is true ++ +.Default +`000` + + +[[hbase.metrics.showTableName]] +*`hbase.metrics.showTableName`*:: ++ +.Description +Whether to include the prefix "tbl.tablename" in per-column family metrics. + If true, for each metric M, per-cf metrics will be reported for tbl.T.cf.CF.M, if false, + per-cf metrics will be aggregated by column-family across tables, and reported for cf.CF.M. + In both cases, the aggregated metric M across tables and cfs will be reported. ++ +.Default +`true` + + +[[hbase.metrics.exposeOperationTimes]] +*`hbase.metrics.exposeOperationTimes`*:: ++ +.Description +Whether to report metrics about time taken performing an + operation on the region server. Get, Put, Delete, Increment, and Append can all + have their times exposed through Hadoop metrics per CF and per region. ++ +.Default +`true` + + +[[hbase.snapshot.enabled]] +*`hbase.snapshot.enabled`*:: ++ +.Description +Set to true to allow snapshots to be taken / restored / cloned. ++ +.Default +`true` + + +[[hbase.snapshot.restore.take.failsafe.snapshot]] +*`hbase.snapshot.restore.take.failsafe.snapshot`*:: ++ +.Description +Set to true to take a snapshot before the restore operation. + The snapshot taken will be used in case of failure, to restore the previous state. + At the end of the restore operation this snapshot will be deleted ++ +.Default +`true` + + +[[hbase.snapshot.restore.failsafe.name]] +*`hbase.snapshot.restore.failsafe.name`*:: ++ +.Description +Name of the failsafe snapshot taken by the restore operation. + You can use the {snapshot.name}, {table.name} and {restore.timestamp} variables + to create a name based on what you are restoring. ++ +.Default +`hbase-failsafe-{snapshot.name}-{restore.timestamp}` + + +[[hbase.server.compactchecker.interval.multiplier]] +*`hbase.server.compactchecker.interval.multiplier`*:: ++ +.Description +The number that determines how often we scan to see if compaction is necessary. + Normally, compactions are done after some events (such as memstore flush), but if + region didn't receive a lot of writes for some time, or due to different compaction + policies, it may be necessary to check it periodically. The interval between checks is + hbase.server.compactchecker.interval.multiplier multiplied by + hbase.server.thread.wakefrequency. ++ +.Default +`1000` + + +[[hbase.lease.recovery.timeout]] +*`hbase.lease.recovery.timeout`*:: ++ +.Description +How long we wait on dfs lease recovery in total before giving up. ++ +.Default +`900000` + + +[[hbase.lease.recovery.dfs.timeout]] +*`hbase.lease.recovery.dfs.timeout`*:: ++ +.Description +How long between dfs recover lease invocations. Should be larger than the sum of + the time it takes for the namenode to issue a block recovery command as part of + datanode; dfs.heartbeat.interval and the time it takes for the primary + datanode, performing block recovery to timeout on a dead datanode; usually + dfs.client.socket-timeout. See the end of HBASE-8389 for more. ++ +.Default +`64000` + + +[[hbase.column.max.version]] +*`hbase.column.max.version`*:: ++ +.Description +New column family descriptors will use this value as the default number of versions + to keep. ++ +.Default +`1` + + +[[hbase.dfs.client.read.shortcircuit.buffer.size]] +*`hbase.dfs.client.read.shortcircuit.buffer.size`*:: ++ +.Description +If the DFSClient configuration + dfs.client.read.shortcircuit.buffer.size is unset, we will + use what is configured here as the short circuit read default + direct byte buffer size. DFSClient native default is 1MB; HBase + keeps its HDFS files open so number of file blocks * 1MB soon + starts to add up and threaten OOME because of a shortage of + direct memory. So, we set it down from the default. Make + it > the default hbase block size set in the HColumnDescriptor + which is usually 64k. + ++ +.Default +`131072` + + +[[hbase.regionserver.checksum.verify]] +*`hbase.regionserver.checksum.verify`*:: ++ +.Description + + If set to true (the default), HBase verifies the checksums for hfile + blocks. HBase writes checksums inline with the data when it writes out + hfiles. HDFS (as of this writing) writes checksums to a separate file + than the data file necessitating extra seeks. Setting this flag saves + some on i/o. Checksum verification by HDFS will be internally disabled + on hfile streams when this flag is set. If the hbase-checksum verification + fails, we will switch back to using HDFS checksums (so do not disable HDFS + checksums! And besides this feature applies to hfiles only, not to WALs). + If this parameter is set to false, then hbase will not verify any checksums, + instead it will depend on checksum verification being done in the HDFS client. + ++ +.Default +`true` + + +[[hbase.hstore.bytes.per.checksum]] +*`hbase.hstore.bytes.per.checksum`*:: ++ +.Description + + Number of bytes in a newly created checksum chunk for HBase-level + checksums in hfile blocks. + ++ +.Default +`16384` + + +[[hbase.hstore.checksum.algorithm]] +*`hbase.hstore.checksum.algorithm`*:: ++ +.Description + + Name of an algorithm that is used to compute checksums. Possible values + are NULL, CRC32, CRC32C. + ++ +.Default +`CRC32` + + +[[hbase.status.published]] +*`hbase.status.published`*:: ++ +.Description + + This setting activates the publication by the master of the status of the region server. + When a region server dies and its recovery starts, the master will push this information + to the client application, to let them cut the connection immediately instead of waiting + for a timeout. + ++ +.Default +`false` + + +[[hbase.status.publisher.class]] +*`hbase.status.publisher.class`*:: ++ +.Description + + Implementation of the status publication with a multicast message. + ++ +.Default +`org.apache.hadoop.hbase.master.ClusterStatusPublisher$MulticastPublisher` + + +[[hbase.status.listener.class]] +*`hbase.status.listener.class`*:: ++ +.Description + + Implementation of the status listener with a multicast message. + ++ +.Default +`org.apache.hadoop.hbase.client.ClusterStatusListener$MulticastListener` + + +[[hbase.status.multicast.address.ip]] +*`hbase.status.multicast.address.ip`*:: ++ +.Description + + Multicast address to use for the status publication by multicast. + ++ +.Default +`226.1.1.3` + + +[[hbase.status.multicast.address.port]] +*`hbase.status.multicast.address.port`*:: ++ +.Description + + Multicast port to use for the status publication by multicast. + ++ +.Default +`16100` + + +[[hbase.dynamic.jars.dir]] +*`hbase.dynamic.jars.dir`*:: ++ +.Description + + The directory from which the custom filter/co-processor jars can be loaded + dynamically by the region server without the need to restart. However, + an already loaded filter/co-processor class would not be un-loaded. See + HBASE-1936 for more details. + ++ +.Default +`${hbase.rootdir}/lib` + + +[[hbase.security.authentication]] +*`hbase.security.authentication`*:: ++ +.Description + + Controls whether or not secure authentication is enabled for HBase. + Possible values are 'simple' (no authentication), and 'kerberos'. + ++ +.Default +`simple` + + +[[hbase.rest.filter.classes]] +*`hbase.rest.filter.classes`*:: ++ +.Description + + Servlet filters for REST service. + ++ +.Default +`org.apache.hadoop.hbase.rest.filter.GzipFilter` + + +[[hbase.master.loadbalancer.class]] +*`hbase.master.loadbalancer.class`*:: ++ +.Description + + Class used to execute the regions balancing when the period occurs. + See the class comment for more on how it works + http://hbase.apache.org/devapidocs/org/apache/hadoop/hbase/master/balancer/StochasticLoadBalancer.html + It replaces the DefaultLoadBalancer as the default (since renamed + as the SimpleLoadBalancer). + ++ +.Default +`org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer` + + +[[hbase.security.exec.permission.checks]] +*`hbase.security.exec.permission.checks`*:: ++ +.Description + + If this setting is enabled and ACL based access control is active (the + AccessController coprocessor is installed either as a system coprocessor + or on a table as a table coprocessor) then you must grant all relevant + users EXEC privilege if they require the ability to execute coprocessor + endpoint calls. EXEC privilege, like any other permission, can be + granted globally to a user, or to a user on a per table or per namespace + basis. For more information on coprocessor endpoints, see the coprocessor + section of the HBase online manual. For more information on granting or + revoking permissions using the AccessController, see the security + section of the HBase online manual. + ++ +.Default +`false` + + +[[hbase.procedure.regionserver.classes]] +*`hbase.procedure.regionserver.classes`*:: ++ +.Description +A comma-separated list of + org.apache.hadoop.hbase.procedure.RegionServerProcedureManager procedure managers that are + loaded by default on the active HRegionServer process. The lifecycle methods (init/start/stop) + will be called by the active HRegionServer process to perform the specific globally barriered + procedure. After implementing your own RegionServerProcedureManager, just put it in + HBase's classpath and add the fully qualified class name here. + ++ +.Default +`` + + +[[hbase.procedure.master.classes]] +*`hbase.procedure.master.classes`*:: ++ +.Description +A comma-separated list of + org.apache.hadoop.hbase.procedure.MasterProcedureManager procedure managers that are + loaded by default on the active HMaster process. A procedure is identified by its signature and + users can use the signature and an instant name to trigger an execution of a globally barriered + procedure. After implementing your own MasterProcedureManager, just put it in HBase's classpath + and add the fully qualified class name here. ++ +.Default +`` + + +[[hbase.coordinated.state.manager.class]] +*`hbase.coordinated.state.manager.class`*:: ++ +.Description +Fully qualified name of class implementing coordinated state manager. ++ +.Default +`org.apache.hadoop.hbase.coordination.ZkCoordinatedStateManager` + + +[[hbase.regionserver.storefile.refresh.period]] +*`hbase.regionserver.storefile.refresh.period`*:: ++ +.Description + + The period (in milliseconds) for refreshing the store files for the secondary regions. 0 + means this feature is disabled. Secondary regions sees new files (from flushes and + compactions) from primary once the secondary region refreshes the list of files in the + region (there is no notification mechanism). But too frequent refreshes might cause + extra Namenode pressure. If the files cannot be refreshed for longer than HFile TTL + (hbase.master.hfilecleaner.ttl) the requests are rejected. Configuring HFile TTL to a larger + value is also recommended with this setting. + ++ +.Default +`0` + + +[[hbase.region.replica.replication.enabled]] +*`hbase.region.replica.replication.enabled`*:: ++ +.Description + + Whether asynchronous WAL replication to the secondary region replicas is enabled or not. + If this is enabled, a replication peer named "region_replica_replication" will be created + which will tail the logs and replicate the mutatations to region replicas for tables that + have region replication > 1. If this is enabled once, disabling this replication also + requires disabling the replication peer using shell or ReplicationAdmin java class. + Replication to secondary region replicas works over standard inter-cluster replication. + So replication, if disabled explicitly, also has to be enabled by setting "hbase.replication" + to true for this feature to work. + ++ +.Default +`false` + + +[[hbase.http.filter.initializers]] +*`hbase.http.filter.initializers`*:: ++ +.Description + + A comma separated list of class names. Each class in the list must extend + org.apache.hadoop.hbase.http.FilterInitializer. The corresponding Filter will + be initialized. Then, the Filter will be applied to all user facing jsp + and servlet web pages. + The ordering of the list defines the ordering of the filters. + The default StaticUserWebFilter add a user principal as defined by the + hbase.http.staticuser.user property. + ++ +.Default +`org.apache.hadoop.hbase.http.lib.StaticUserWebFilter` + + +[[hbase.security.visibility.mutations.checkauths]] +*`hbase.security.visibility.mutations.checkauths`*:: ++ +.Description + + This property if enabled, will check whether the labels in the visibility expression are associated + with the user issuing the mutation + ++ +.Default +`false` + + +[[hbase.http.max.threads]] +*`hbase.http.max.threads`*:: ++ +.Description + + The maximum number of threads that the HTTP Server will create in its + ThreadPool. + ++ +.Default +`10` + + +[[hbase.replication.rpc.codec]] +*`hbase.replication.rpc.codec`*:: ++ +.Description + + The codec that is to be used when replication is enabled so that + the tags are also replicated. This is used along with HFileV3 which + supports tags in them. If tags are not used or if the hfile version used + is HFileV2 then KeyValueCodec can be used as the replication codec. Note that + using KeyValueCodecWithTags for replication when there are no tags causes no harm. + ++ +.Default +`org.apache.hadoop.hbase.codec.KeyValueCodecWithTags` + + +[[hbase.http.staticuser.user]] +*`hbase.http.staticuser.user`*:: ++ +.Description + + The user name to filter as, on static web filters + while rendering content. An example use is the HDFS + web UI (user to be used for browsing files). + ++ +.Default +`dr.stack` + + +[[hbase.regionserver.handler.abort.on.error.percent]] +*`hbase.regionserver.handler.abort.on.error.percent`*:: ++ +.Description +The percent of region server RPC threads failed to abort RS. + -1 Disable aborting; 0 Abort if even a single handler has died; + 0.x Abort only when this percent of handlers have died; + 1 Abort only all of the handers have died. ++ +.Default +`0.5` + + \ No newline at end of file
http://git-wip-us.apache.org/repos/asf/hbase/blob/cb77a925/src/main/asciidoc/_chapters/hbase_apis.adoc ---------------------------------------------------------------------- diff --git a/src/main/asciidoc/_chapters/hbase_apis.adoc b/src/main/asciidoc/_chapters/hbase_apis.adoc new file mode 100644 index 0000000..1fed946 --- /dev/null +++ b/src/main/asciidoc/_chapters/hbase_apis.adoc @@ -0,0 +1,137 @@ +//// +/** + * + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +//// + +[[hbase_apis]] += Apache HBase APIs +:doctype: book +:numbered: +:toc: left +:icons: font +:experimental: + +This chapter provides information about performing operations using HBase native APIs. +This information is not exhaustive, and provides a quick reference in addition to the link:http://hbase.apache.org/apidocs/index.html[User API + Reference]. +The examples here are not comprehensive or complete, and should be used for purposes of illustration only. + +Apache HBase also works with multiple external APIs. +See <<external_apis,external apis>> for more information. + +== Examples + +.Create a Table Using Java +==== +This example has been tested on HBase 0.96.1.1. + +[source,java] +---- + +package com.example.hbase.admin; + +import java.io.IOException; + +import org.apache.hadoop.hbase.HBaseConfiguration; +import org.apache.hadoop.hbase.HColumnDescriptor; +import org.apache.hadoop.hbase.HTableDescriptor; +import org.apache.hadoop.hbase.TableName; +import org.apache.hadoop.hbase.client.HBaseAdmin; +import org.apache.hadoop.hbase.io.compress.Compression.Algorithm; +import org.apache.hadoop.conf.Configuration; + +import static com.example.hbase.Constants.*; + +public class CreateSchema { + + public static void createOrOverwrite(HBaseAdmin admin, HTableDescriptor table) throws IOException { + if (admin.tableExists(table.getName())) { + admin.disableTable(table.getName()); + admin.deleteTable(table.getName()); + } + admin.createTable(table); + } + + public static void createSchemaTables (Configuration config) { + try { + final HBaseAdmin admin = new HBaseAdmin(config); + HTableDescriptor table = new HTableDescriptor(TableName.valueOf(TABLE_NAME)); + table.addFamily(new HColumnDescriptor(CF_DEFAULT).setCompressionType(Algorithm.SNAPPY)); + + System.out.print("Creating table. "); + createOrOverwrite(admin, table); + System.out.println(" Done."); + + admin.close(); + } catch (Exception e) { + e.printStackTrace(); + System.exit(-1); + } + } + + +} +---- +==== + +.Add, Modify, and Delete a Table +==== +This example has been tested on HBase 0.96.1.1. + +[source,java] +---- + +public static void upgradeFrom0 (Configuration config) { + + try { + final HBaseAdmin admin = new HBaseAdmin(config); + TableName tableName = TableName.valueOf(TABLE_ASSETMETA); + HTableDescriptor table_assetmeta = new HTableDescriptor(tableName); + table_assetmeta.addFamily(new HColumnDescriptor(CF_DEFAULT).setCompressionType(Algorithm.SNAPPY)); + + // Create a new table. + + System.out.print("Creating table_assetmeta. "); + admin.createTable(table_assetmeta); + System.out.println(" Done."); + + // Update existing table + HColumnDescriptor newColumn = new HColumnDescriptor("NEWCF"); + newColumn.setCompactionCompressionType(Algorithm.GZ); + newColumn.setMaxVersions(HConstants.ALL_VERSIONS); + admin.addColumn(tableName, newColumn); + + // Disable an existing table + admin.disableTable(tableName); + + // Delete an existing column family + admin.deleteColumn(tableName, CF_DEFAULT); + + // Delete a table (Need to be disabled first) + admin.deleteTable(tableName); + + + admin.close(); + } catch (Exception e) { + e.printStackTrace(); + System.exit(-1); + } + } +---- +==== http://git-wip-us.apache.org/repos/asf/hbase/blob/cb77a925/src/main/asciidoc/_chapters/hbase_history.adoc ---------------------------------------------------------------------- diff --git a/src/main/asciidoc/_chapters/hbase_history.adoc b/src/main/asciidoc/_chapters/hbase_history.adoc new file mode 100644 index 0000000..de4aff5 --- /dev/null +++ b/src/main/asciidoc/_chapters/hbase_history.adoc @@ -0,0 +1,37 @@ +//// +/** + * + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +//// + +[appendix] +[[hbase.history]] +== HBase History + +:doctype: book +:numbered: +:toc: left +:icons: font +:experimental: + +* 2006: link:http://research.google.com/archive/bigtable.html[BigTable] paper published by Google. +* 2006 (end of year): HBase development starts. +* 2008: HBase becomes Hadoop sub-project. +* 2010: HBase becomes Apache top-level project. + +:numbered: http://git-wip-us.apache.org/repos/asf/hbase/blob/cb77a925/src/main/asciidoc/_chapters/hbck_in_depth.adoc ---------------------------------------------------------------------- diff --git a/src/main/asciidoc/_chapters/hbck_in_depth.adoc b/src/main/asciidoc/_chapters/hbck_in_depth.adoc new file mode 100644 index 0000000..1b30c59 --- /dev/null +++ b/src/main/asciidoc/_chapters/hbck_in_depth.adoc @@ -0,0 +1,212 @@ +//// +/** + * + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +//// + +[appendix] +[[hbck.in.depth]] +== hbck In Depth +:doctype: book +:numbered: +:toc: left +:icons: font +:experimental: + +HBaseFsck (hbck) is a tool for checking for region consistency and table integrity problems and repairing a corrupted HBase. +It works in two basic modes -- a read-only inconsistency identifying mode and a multi-phase read-write repair mode. + +=== Running hbck to identify inconsistencies + +To check to see if your HBase cluster has corruptions, run hbck against your HBase cluster: + +[source,bourne] +---- + +$ ./bin/hbase hbck +---- + +At the end of the commands output it prints OK or tells you the number of INCONSISTENCIES present. +You may also want to run run hbck a few times because some inconsistencies can be transient (e.g. +cluster is starting up or a region is splitting). Operationally you may want to run hbck regularly and setup alert (e.g. +via nagios) if it repeatedly reports inconsistencies . A run of hbck will report a list of inconsistencies along with a brief description of the regions and tables affected. +The using the `-details` option will report more details including a representative listing of all the splits present in all the tables. + +[source,bourne] +---- + +$ ./bin/hbase hbck -details +---- + +If you just want to know if some tables are corrupted, you can limit hbck to identify inconsistencies in only specific tables. +For example the following command would only attempt to check table TableFoo and TableBar. +The benefit is that hbck will run in less time. + +[source,bourne] +---- + +$ ./bin/hbase hbck TableFoo TableBar +---- + +=== Inconsistencies + +If after several runs, inconsistencies continue to be reported, you may have encountered a corruption. +These should be rare, but in the event they occur newer versions of HBase include the hbck tool enabled with automatic repair options. + +There are two invariants that when violated create inconsistencies in HBase: + +* HBase's region consistency invariant is satisfied if every region is assigned and deployed on exactly one region server, and all places where this state kept is in accordance. +* HBase's table integrity invariant is satisfied if for each table, every possible row key resolves to exactly one region. + +Repairs generally work in three phases -- a read-only information gathering phase that identifies inconsistencies, a table integrity repair phase that restores the table integrity invariant, and then finally a region consistency repair phase that restores the region consistency invariant. +Starting from version 0.90.0, hbck could detect region consistency problems report on a subset of possible table integrity problems. +It also included the ability to automatically fix the most common inconsistency, region assignment and deployment consistency problems. +This repair could be done by using the `-fix` command line option. +These problems close regions if they are open on the wrong server or on multiple region servers and also assigns regions to region servers if they are not open. + +Starting from HBase versions 0.90.7, 0.92.2 and 0.94.0, several new command line options are introduced to aid repairing a corrupted HBase. +This hbck sometimes goes by the nickname ``uberhbck''. Each particular version of uber hbck is compatible with the HBase's of the same major version (0.90.7 uberhbck can repair a 0.90.4). However, versions <=0.90.6 and versions <=0.92.1 may require restarting the master or failing over to a backup master. + +=== Localized repairs + +When repairing a corrupted HBase, it is best to repair the lowest risk inconsistencies first. +These are generally region consistency repairs -- localized single region repairs, that only modify in-memory data, ephemeral zookeeper data, or patch holes in the META table. +Region consistency requires that the HBase instance has the state of the region's data in HDFS (.regioninfo files), the region's row in the hbase:meta table., and region's deployment/assignments on region servers and the master in accordance. +Options for repairing region consistency include: + +* `-fixAssignments` (equivalent to the 0.90 `-fix` option) repairs unassigned, incorrectly assigned or multiply assigned regions. +* `-fixMeta` which removes meta rows when corresponding regions are not present in HDFS and adds new meta rows if they regions are present in HDFS while not in META. To fix deployment and assignment problems you can run this command: + +[source,bourne] +---- + +$ ./bin/hbase hbck -fixAssignments +---- + +To fix deployment and assignment problems as well as repairing incorrect meta rows you can run this command: + +[source,bourne] +---- + +$ ./bin/hbase hbck -fixAssignments -fixMeta +---- + +There are a few classes of table integrity problems that are low risk repairs. +The first two are degenerate (startkey == endkey) regions and backwards regions (startkey > endkey). These are automatically handled by sidelining the data to a temporary directory (/hbck/xxxx). The third low-risk class is hdfs region holes. +This can be repaired by using the: + +* `-fixHdfsHoles` option for fabricating new empty regions on the file system. + If holes are detected you can use -fixHdfsHoles and should include -fixMeta and -fixAssignments to make the new region consistent. + +[source,bourne] +---- + +$ ./bin/hbase hbck -fixAssignments -fixMeta -fixHdfsHoles +---- + +Since this is a common operation, we've added a the `-repairHoles` flag that is equivalent to the previous command: + +[source,bourne] +---- + +$ ./bin/hbase hbck -repairHoles +---- + +If inconsistencies still remain after these steps, you most likely have table integrity problems related to orphaned or overlapping regions. + +=== Region Overlap Repairs + +Table integrity problems can require repairs that deal with overlaps. +This is a riskier operation because it requires modifications to the file system, requires some decision making, and may require some manual steps. +For these repairs it is best to analyze the output of a `hbck -details` run so that you isolate repairs attempts only upon problems the checks identify. +Because this is riskier, there are safeguard that should be used to limit the scope of the repairs. +WARNING: This is a relatively new and have only been tested on online but idle HBase instances (no reads/writes). Use at your own risk in an active production environment! The options for repairing table integrity violations include: + +* `-fixHdfsOrphans` option for ``adopting'' a region directory that is missing a region metadata file (the .regioninfo file). +* `-fixHdfsOverlaps` ability for fixing overlapping regions + +When repairing overlapping regions, a region's data can be modified on the file system in two ways: 1) by merging regions into a larger region or 2) by sidelining regions by moving data to ``sideline'' directory where data could be restored later. +Merging a large number of regions is technically correct but could result in an extremely large region that requires series of costly compactions and splitting operations. +In these cases, it is probably better to sideline the regions that overlap with the most other regions (likely the largest ranges) so that merges can happen on a more reasonable scale. +Since these sidelined regions are already laid out in HBase's native directory and HFile format, they can be restored by using HBase's bulk load mechanism. +The default safeguard thresholds are conservative. +These options let you override the default thresholds and to enable the large region sidelining feature. + +* `-maxMerge <n>` maximum number of overlapping regions to merge +* `-sidelineBigOverlaps` if more than maxMerge regions are overlapping, sideline attempt to sideline the regions overlapping with the most other regions. +* `-maxOverlapsToSideline <n>` if sidelining large overlapping regions, sideline at most n regions. + +Since often times you would just want to get the tables repaired, you can use this option to turn on all repair options: + +* `-repair` includes all the region consistency options and only the hole repairing table integrity options. + +Finally, there are safeguards to limit repairs to only specific tables. +For example the following command would only attempt to check and repair table TableFoo and TableBar. + +---- + +$ ./bin/hbase hbck -repair TableFoo TableBar +---- + +==== Special cases: Meta is not properly assigned + +There are a few special cases that hbck can handle as well. +Sometimes the meta table's only region is inconsistently assigned or deployed. +In this case there is a special `-fixMetaOnly` option that can try to fix meta assignments. + +---- + +$ ./bin/hbase hbck -fixMetaOnly -fixAssignments +---- + +==== Special cases: HBase version file is missing + +HBase's data on the file system requires a version file in order to start. +If this flie is missing, you can use the `-fixVersionFile` option to fabricating a new HBase version file. +This assumes that the version of hbck you are running is the appropriate version for the HBase cluster. + +==== Special case: Root and META are corrupt. + +The most drastic corruption scenario is the case where the ROOT or META is corrupted and HBase will not start. +In this case you can use the OfflineMetaRepair tool create new ROOT and META regions and tables. +This tool assumes that HBase is offline. +It then marches through the existing HBase home directory, loads as much information from region metadata files (.regioninfo files) as possible from the file system. +If the region metadata has proper table integrity, it sidelines the original root and meta table directories, and builds new ones with pointers to the region directories and their data. + +---- + +$ ./bin/hbase org.apache.hadoop.hbase.util.hbck.OfflineMetaRepair +---- + +NOTE: This tool is not as clever as uberhbck but can be used to bootstrap repairs that uberhbck can complete. +If the tool succeeds you should be able to start hbase and run online repairs if necessary. + +==== Special cases: Offline split parent + +Once a region is split, the offline parent will be cleaned up automatically. +Sometimes, daughter regions are split again before their parents are cleaned up. +HBase can clean up parents in the right order. +However, there could be some lingering offline split parents sometimes. +They are in META, in HDFS, and not deployed. +But HBase can't clean them up. +In this case, you can use the `-fixSplitParents` option to reset them in META to be online and not split. +Therefore, hbck can merge them with other regions if fixing overlapping regions option is used. + +This option should not normally be used, and it is not in `-fixAll`. + +:numbered:
