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https://issues.apache.org/jira/browse/HBASE-2312?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13138865#comment-13138865
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Phabricator commented on HBASE-2312:
------------------------------------
nspiegelberg has commented on the revision "HBASE-2312 [jira] Possible data
loss when RS goes into GC pause while rolling HLog".
sending a new diff. note that Phabricator has a nifty diff-compare tool for
you to make it easy to see my code changes in response to your commentary :)
INLINE COMMENTS
src/main/java/org/apache/hadoop/hbase/master/MasterFileSystem.java:223
Prakash did the Exception handling part of this code, so I'll let him follow up
if you need more info. Basically, we are still in the initialization phase (we
are in the server abort thread right now), where server abort should be used
during normal operation.
REVISION DETAIL
https://reviews.facebook.net/D99
> Possible data loss when RS goes into GC pause while rolling HLog
> ----------------------------------------------------------------
>
> Key: HBASE-2312
> URL: https://issues.apache.org/jira/browse/HBASE-2312
> Project: HBase
> Issue Type: Bug
> Components: master, regionserver
> Affects Versions: 0.90.0
> Reporter: Karthik Ranganathan
> Assignee: Nicolas Spiegelberg
> Priority: Critical
> Fix For: 0.92.0
>
> Attachments: D99.1.patch
>
>
> There is a very corner case when bad things could happen(ie data loss):
> 1) RS #1 is going to roll its HLog - not yet created the new one, old one
> will get no more writes
> 2) RS #1 enters GC Pause of Death
> 3) Master lists HLog files of RS#1 that is has to split as RS#1 is dead,
> starts splitting
> 4) RS #1 wakes up, created the new HLog (previous one was rolled) and
> appends an edit - which is lost
> The following seems like a possible solution:
> 1) Master detects RS#1 is dead
> 2) The master renames the /hbase/.logs/<regionserver name> directory to
> something else (say /hbase/.logs/<regionserver name>-dead)
> 3) Add mkdir support (as opposed to mkdirs) to HDFS - so that a file
> create fails if the directory doesn't exist. Dhruba tells me this is very
> doable.
> 4) RS#1 comes back up and is not able create the new hlog. It restarts
> itself.
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