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https://issues.apache.org/jira/browse/HBASE-2312?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13142645#comment-13142645
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Hudson commented on HBASE-2312:
-------------------------------
Integrated in HBase-TRUNK #2402 (See
[https://builds.apache.org/job/HBase-TRUNK/2402/])
HBASE-2312 [jira] Possible data loss when RS goes into GC pause while
rolling
HLog
Summary:
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.
Test Plan: EMPTY
Reviewers: JIRA, stack, khemani
Reviewed By: khemani
CC: tedyu, nspiegelberg, stack, Kannan, khemani, jgray
Differential Revision: 99
nspiegelberg :
Files :
*
/hbase/trunk/src/main/java/org/apache/hadoop/hbase/master/MasterFileSystem.java
*
/hbase/trunk/src/main/java/org/apache/hadoop/hbase/master/handler/ServerShutdownHandler.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLog.java
*
/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogSplitter.java
*
/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogWriter.java
*
/hbase/trunk/src/main/java/org/apache/hadoop/hbase/replication/regionserver/ReplicationSource.java
*
/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestHLogSplit.java
> 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, D99.2.patch, D99.3.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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