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Nicolas Spiegelberg commented on HBASE-2312: -------------------------------------------- @stack: since we have proper reflection, can we not apply this jira & mark the test as broken? that way, customers can have this fix if they upgrade to the proper version of HDFS instead of requiring an HBase upgrade as well > 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: 0.94.0 > > > 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. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira