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https://issues.apache.org/jira/browse/HBASE-14004?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15046395#comment-15046395
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Duo Zhang commented on HBASE-14004:
-----------------------------------

{quote}
 If e don't persist this acked length, during failover we still will read until 
EOF?
{quote}
It depends on the file state. If it is already closed, then we could use the 
file length get from namenode. If it is still opened for writing, then we 
should ack for the acked length. You could already get the acked length unless 
the RS is crashed, but if the RS is crashed, then the file will finally be 
closed by NN.

> [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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