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https://issues.apache.org/jira/browse/HDFS-4721?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13643246#comment-13643246
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Hudson commented on HDFS-4721:
------------------------------
Integrated in Hadoop-trunk-Commit #3673 (See
[https://builds.apache.org/job/Hadoop-trunk-Commit/3673/])
HDFS-4721. Speed up lease recovery by avoiding stale datanodes and choosing
the datanode with the most recent heartbeat as the primary. Contributed by
Varun Sharma (Revision 1476399)
Result = SUCCESS
szetszwo :
http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1476399
Files :
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockInfoUnderConstruction.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockInfoUnderConstruction.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestHeartbeatHandling.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestPipelinesFailover.java
> Speed up lease/block recovery when DN fails and a block goes into recovery
> --------------------------------------------------------------------------
>
> Key: HDFS-4721
> URL: https://issues.apache.org/jira/browse/HDFS-4721
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 2.0.3-alpha
> Reporter: Varun Sharma
> Assignee: Varun Sharma
> Fix For: 2.0.5-beta
>
> Attachments: 4721-branch2.patch, 4721-trunk.patch,
> 4721-trunk-v2.patch, 4721-trunk-v3.patch, 4721-trunk-v4.patch, 4721-v2.patch,
> 4721-v3.patch, 4721-v4.patch, 4721-v5.patch, 4721-v6.patch, 4721-v7.patch,
> 4721-v8.patch
>
>
> This was observed while doing HBase WAL recovery. HBase uses append to write
> to its write ahead log. So initially the pipeline is setup as
> DN1 --> DN2 --> DN3
> This WAL needs to be read when DN1 fails since it houses the HBase
> regionserver for the WAL.
> HBase first recovers the lease on the WAL file. During recovery, we choose
> DN1 as the primary DN to do the recovery even though DN1 has failed and is
> not heartbeating any more.
> Avoiding the stale DN1 would speed up recovery and reduce hbase MTTR. There
> are two options.
> a) Ride on HDFS 3703 and if stale node detection is turned on, we do not
> choose stale datanodes (typically not heart beated for 20-30 seconds) as
> primary DN(s)
> b) We sort the replicas in order of last heart beat and always pick the ones
> which gave the most recent heart beat
> Going to the dead datanode increases lease + block recovery since the block
> goes into UNDER_RECOVERY state even though no one is recovering it actively.
> Please let me know if this makes sense. If yes, whether we should move
> forward with a) or b).
> Thanks
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