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https://issues.apache.org/jira/browse/HBASE-14004?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14999866#comment-14999866
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Yu Li commented on HBASE-14004:
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[~chenheng] [~Apache9]
Sorry for the late response, somehow didn't notice the jira update mail. See
your point now, thanks for the explanation.
{quote}
I do not know the details that if hflush will call namenode to update length
{quote}
Checking the code, SyncRunner will call ProtobufLogWriter#sync and finally call
DataOutputStream#hflush, there we could know it will only call nn to update
length when new block created, but won't while filling one already created one.
{quote}
I think we need to find a way to make sure whether the WAL is actually
persisted at HDFS
{quote}
Agree. Just notice you've created HBASE-14790 and let's discuss more details
there. :-)
> [Replication] Inconsistency between Memstore and WAL may result in data in
> remote cluster that is not in the origin
> -------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-14004
> URL: https://issues.apache.org/jira/browse/HBASE-14004
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Reporter: He Liangliang
> Priority: Critical
> Labels: replication, wal
>
> Looks like the current write path can cause inconsistency between
> memstore/hfile and WAL which cause the slave cluster has more data than the
> master cluster.
> The simplified write path looks like:
> 1. insert record into Memstore
> 2. write record to WAL
> 3. sync WAL
> 4. rollback Memstore if 3 fails
> It's possible that the HDFS sync RPC call fails, but the data is already
> (may partially) transported to the DNs which finally get persisted. As a
> result, the handler will rollback the Memstore and the later flushed HFile
> will also skip this record.
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