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From andytaylor <...@git.apache.org>
Subject [GitHub] activemq-artemis issue #1747: [WIP] NO-JIRA DISCUSS Replica use operationcon...
Date Thu, 04 Jan 2018 10:50:00 GMT
Github user andytaylor commented on the issue:

    https://github.com/apache/activemq-artemis/pull/1747
  
    Michael is correct, that's what I meant. Let me explain how this works. 
    
    Every record that is written to the journal is also sent to the backup. 
    Once the backup receives the packet it responds with an ack and in parallel writes it
to disc.
    When the live crashes the back up fsyncs and then starts.
    
    There is a small window between when the live crashes and when the fsync occurs that the
backup may crash, but this is unlikely to happen and you stil have data consistency as the
journal is on the live.
    
    The caveat here is if the disc on the live was destroyed, but again the window is so small
there are more likely scenarios that we could improve from a crash pov.
    
    @shoukunhuai  Why don't you explain your use case, not in an implementation way but something
like 'when x happens I want to avoid y'.


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