Possible data loss when RS goes into GC pause while rolling HLog
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Key: HBASE-2312
URL: https://issues.apache.org/jira/browse/HBASE-2312
Project: Hadoop HBase
Issue Type: Bug
Components: master, regionserver
Affects Versions: 0.20.3
Reporter: Karthik Ranganathan
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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