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https://issues.apache.org/jira/browse/HBASE-20723?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16514086#comment-16514086
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Sean Busbey commented on HBASE-20723:
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Can we make the subject better convey the problem for downstream users?
bq. WALSplitter uses the rootDir, which is walDir, as the recovered edits root
path
would this rephrasing be accurate?
bq. Custom hbase.wal.dir results in dataloss because we write recovered edits
into a different place than where the recovering region server looks for them.
And then this for the start of the description:
bq. 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 writes that
had not flushed prior to loss of a server.
> WALSplitter uses the rootDir, which is walDir, as the recovered edits root
> path
> -------------------------------------------------------------------------------
>
> 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
> Attachments: 20723.v1.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
>
>
> 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:[email protected]]/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], [[email protected]] Attached the logs for quick review.
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