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https://issues.apache.org/jira/browse/HBASE-14004?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15048171#comment-15048171
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Heng Chen commented on HBASE-14004:
-----------------------------------
{quote}
And if we don't use hsync, I think we need not change the logic of replicator
which means we needn't only transfer data that is hflushed because all entries
in WAL should finally be in memstore, right?
{quote}
Think about this situation.
In write path, some entries hflushed but not acked, so we close old WAL with
acked length, and try to write this entries into new WAL, then RS crashed.
Slave maybe has replicate this entries but RS after recovery in master will
lost them, right?
> [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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