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https://issues.apache.org/jira/browse/HDFS-4721?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13638558#comment-13638558
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Hadoop QA commented on HDFS-4721:
---------------------------------
{color:red}-1 overall{color}. Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12579904/4721-v2.patch
against trunk revision .
{color:green}+1 @author{color}. The patch does not contain any @author
tags.
{color:red}-1 tests included{color}. The patch doesn't appear to include
any new or modified tests.
Please justify why no new tests are needed for this
patch.
Also please list what manual steps were performed to
verify this patch.
{color:red}-1 javac{color}. The applied patch generated 1367 javac
compiler warnings (more than the trunk's current 1366 warnings).
{color:green}+1 javadoc{color}. The javadoc tool did not generate any
warning messages.
{color:green}+1 eclipse:eclipse{color}. The patch built with
eclipse:eclipse.
{color:red}-1 findbugs{color}. The patch appears to introduce 1 new
Findbugs (version 1.3.9) warnings.
{color:green}+1 release audit{color}. The applied patch does not increase
the total number of release audit warnings.
{color:green}+1 core tests{color}. The patch passed unit tests in
hadoop-hdfs-project/hadoop-hdfs.
{color:green}+1 contrib tests{color}. The patch passed contrib unit tests.
Test results:
https://builds.apache.org/job/PreCommit-HDFS-Build/4285//testReport/
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HDFS-Build/4285//artifact/trunk/patchprocess/newPatchFindbugsWarningshadoop-hdfs.html
Javac warnings:
https://builds.apache.org/job/PreCommit-HDFS-Build/4285//artifact/trunk/patchprocess/diffJavacWarnings.txt
Console output: https://builds.apache.org/job/PreCommit-HDFS-Build/4285//console
This message is automatically generated.
> 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
> Fix For: 2.0.4-alpha
>
> Attachments: 4721-hadoop2.patch, 4721-v2.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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