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https://issues.apache.org/jira/browse/HBASE-20723?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16548560#comment-16548560
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Sakthi commented on HBASE-20723:
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[~yuzhih...@gmail.com] [~mdrob] [~busbey], I see that this hasn't been
backported to 1.2 yet? Any specific reasons?
> Custom hbase.wal.dir results in data loss because we write recovered edits
> into a different place than where the recovering region server looks for them
> --------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-20723
> URL: https://issues.apache.org/jira/browse/HBASE-20723
> Project: HBase
> Issue Type: Bug
> Components: Recovery, wal
> Affects Versions: 1.4.0, 1.4.1, 1.4.2, 1.4.3, 1.4.4, 2.0.0
> Reporter: Rohan Pednekar
> Assignee: Ted Yu
> Priority: Critical
> Fix For: 2.1.0, 1.5.0, 1.4.6
>
> Attachments: 20723.branch-1.txt, 20723.branch-2.txt, 20723.v1.txt,
> 20723.v10.txt, 20723.v2.txt, 20723.v3.txt, 20723.v4.txt, 20723.v5.txt,
> 20723.v5.txt, 20723.v6.txt, 20723.v7.txt, 20723.v8.txt, 20723.v9.txt, logs.zip
>
>
> Description:
> When custom hbase.wal.dir is configured the recovery system uses it in place
> of the HBase root dir and thus constructs an incorrect path for recovered
> edits when splitting WALs. This causes the recovery code in Region Servers to
> believe there are no recovered edits to replay, which causes a loss of writes
> that had not flushed prior to loss of a server.
>
> Reproduction:
> This is an Azure HDInsight HBase cluster with HDP 2.6. and HBase
> 1.1.2.2.6.3.2-14
> By default the underlying data is going to wasb://xxxxx@yyyyy/hbase
> I tried to move WAL folders to HDFS, which is the SSD mounted on each VM at
> /mnt.
> hbase.wal.dir= hdfs://mycluster/walontest
> hbase.wal.dir.perms=700
> hbase.rootdir.perms=700
> hbase.rootdir=
> wasb://XYZ[@hbaseperf.core.net|mailto:duohbase5ds...@duohbaseperf.blob.core.windows.net]/hbase
> Procedure to reproduce this issue:
> 1. create a table in hbase shell
> 2. insert a row in hbase shell
> 3. reboot the VM which hosts that region
> 4. scan the table in hbase shell and it is empty
> Looking at the region server logs:
> {code:java}
> 2018-06-12 22:08:40,455 INFO [RS_LOG_REPLAY_OPS-wn2-duohba:16020-0-Writer-1]
> wal.WALSplitter: This region's directory doesn't exist:
> hdfs://mycluster/walontest/data/default/tb1/b7fd7db5694eb71190955292b3ff7648.
> It is very likely that it was already split so it's safe to discard those
> edits.
> {code}
> The log split/replay ignored actual WAL due to WALSplitter is looking for the
> region directory in the hbase.wal.dir we specified rather than the
> hbase.rootdir.
> Looking at the source code,
>
> [https://github.com/apache/hbase/blob/master/hbase-server/src/main/java/org/apache/hadoop/hbase/wal/WALSplitter.java]
> it uses the rootDir, which is walDir, as the tableDir root path.
> So if we use HBASE-17437, waldir and hbase rootdir are in different path or
> even in different filesystem, then the #5 uses walDir as tableDir is
> apparently wrong.
> CC: [~zyork], [~yuzhih...@gmail.com] Attached the logs for quick review.
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