[jira] [Commented] (HBASE-14004) [Replication] Inconsistency between Memstore and WAL may result in data in remote cluster that is not in the origin

["Yu Li (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-14004?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14999866#comment-14999866 ] 

Yu Li commented on HBASE-14004:
-------------------------------

[~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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