[ 
https://issues.apache.org/jira/browse/HBASE-14004?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15044318#comment-15044318
 ] 

Heng Chen commented on HBASE-14004:
-----------------------------------

{quote}
If only RS crashed, DNs not, there is no data loss because they are hflushed to 
DNs' memory.
{quote}
If i understand correctly,  this is my thought.
If one hlush failed, we close old WAL and write entries not hsync to new WAL, 
right?  You close old WAL as old acked length, right?  'Acked length' is 
updated by hsync, right?  If RS crashed at this time, when WAL replayed by 
other RS,  the entries not hsynced in Queue (whatever it is) will lost, 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.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Reply via email to