[
https://issues.apache.org/jira/browse/HDFS-10360?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Lei (Eddy) Xu updated HDFS-10360:
---------------------------------
Labels: dataloss datanode (was: )
> DataNode may format directory and lose blocks if current/VERSION is missing
> ---------------------------------------------------------------------------
>
> Key: HDFS-10360
> URL: https://issues.apache.org/jira/browse/HDFS-10360
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: datanode
> Reporter: Wei-Chiu Chuang
> Assignee: Wei-Chiu Chuang
> Labels: dataloss, datanode
> Fix For: 2.9.0, 3.0.0-alpha1
>
> Attachments: HDFS-10360.001.patch, HDFS-10360.002.patch,
> HDFS-10360.003.patch, HDFS-10360.004.patch, HDFS-10360.004.patch,
> HDFS-10360.005.patch, HDFS-10360.007.patch
>
>
> Under certain circumstances, if the current/VERSION of a storage directory is
> missing, DataNode may format the storage directory even though _block files
> are not missing_.
> This is very easy to reproduce. Simply launch a HDFS cluster and create some
> files. Delete current/VERSION, and restart the data node.
> After the restart, the data node will format the directory and remove all
> existing block files:
> {noformat}
> 2016-05-03 12:57:15,387 INFO org.apache.hadoop.hdfs.server.common.Storage:
> Lock on /data/dfs/dn/in_use.lock acquired by nodename
> 5...@weichiu-dn-2.vpc.cloudera.com
> 2016-05-03 12:57:15,389 INFO org.apache.hadoop.hdfs.server.common.Storage:
> Storage directory /data/dfs/dn is not formatted for
> BP-787466439-172.26.24.43-1462305406642
> 2016-05-03 12:57:15,389 INFO org.apache.hadoop.hdfs.server.common.Storage:
> Formatting ...
> 2016-05-03 12:57:15,464 INFO org.apache.hadoop.hdfs.server.common.Storage:
> Analyzing storage directories for bpid BP-787466439-172.26.24.43-1462305406642
> 2016-05-03 12:57:15,464 INFO org.apache.hadoop.hdfs.server.common.Storage:
> Locking is disabled for
> /data/dfs/dn/current/BP-787466439-172.26.24.43-1462305406642
> 2016-05-03 12:57:15,465 INFO org.apache.hadoop.hdfs.server.common.Storage:
> Block pool storage directory
> /data/dfs/dn/current/BP-787466439-172.26.24.43-1462305406642 is not formatted
> for BP-787466439-172
> .26.24.43-1462305406642
> 2016-05-03 12:57:15,465 INFO org.apache.hadoop.hdfs.server.common.Storage:
> Formatting ...
> 2016-05-03 12:57:15,465 INFO org.apache.hadoop.hdfs.server.common.Storage:
> Formatting block pool BP-787466439-172.26.24.43-1462305406642 directory
> /data/dfs/dn/current/BP-787466439-172.26.24.43-1462305406642/current
> {noformat}
> The bug is: DataNode assumes that if none of {{current/VERSION}},
> {{previous/}}, {{previous.tmp/}}, {{removed.tmp/}}, {{finalized.tmp/}} and
> {{lastcheckpoint.tmp/}} exists, the storage directory contains nothing
> important to HDFS and decides to format it.
> https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/Storage.java#L526-L545
> However, block files may still exist, and in my opinion, we should do
> everything possible to retain the block files.
> I have two suggestions:
> # check if {{current/}} directory is empty. If not, throw an
> InconsistentFSStateException in {{Storage#analyzeStorage}} instead of
> asumming its not formatted. Or,
> # In {{Storage#clearDirectory}}, before it formats the storage directory,
> rename or move {{current/}} directory. Also, log whatever is being
> renamed/moved.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org
