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https://issues.apache.org/jira/browse/HBASE-2312?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12893268#action_12893268
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HBase Review Board commented on HBASE-2312:
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Message from: "Todd Lipcon" <[email protected]>
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http://review.cloudera.org/r/396/#review513
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This looks good, except that it requires the HDFS patches to be in place to
even compile. Although I think it's OK to not fix the bug in the case that
we're on stock HDFS, I think we still need to be able to run, buggily.
Did we determine that all of the other solutions were flawed/too complicated?
trunk/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
<http://review.cloudera.org/r/396/#comment2061>
Check return value of rename (this is one of those stupid APIs that returns
false instead of throwing)
trunk/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
<http://review.cloudera.org/r/396/#comment2062>
rather than reassigning, just pass splitDir below?
trunk/src/main/java/org/apache/hadoop/hbase/master/ProcessServerShutdown.java
<http://review.cloudera.org/r/396/#comment2064>
extract "-splitting" out to a constant?
Or can we move some of this common code into HLog?
trunk/src/main/java/org/apache/hadoop/hbase/master/ProcessServerShutdown.java
<http://review.cloudera.org/r/396/#comment2063>
maybe:
assert !(logDirExists && splitDirExists) : "Both " + rsLogDir + " and " +
rsSplitDir + " exist";
so if the assertion failure happens it's more understandable
- Todd
> 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: 0.20.3
> Reporter: Karthik Ranganathan
> Assignee: Nicolas Spiegelberg
>
> 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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