[jira] [Commented] (HBASE-9465) HLog entries are not pushed to peer clusters serially when region-move or RS failure in master cluster

["Jean-Daniel Cryans (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-9465?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13762105#comment-13762105 ] 

Jean-Daniel Cryans commented on HBASE-9465:
-------------------------------------------

Same comment as on HBASE-9469:

[~lhofhansl] has a blog post that covers this: http://hadoop-hbase.blogspot.com/2012/01/replication-for-ha-and-dr.html

Basically you need to enable KEEP_DELETED_CELLS on your families. I have a draft for a new piece of documentation that we could add to the ref guide that I should probably contribute :)
                
> HLog entries are not pushed to peer clusters serially when region-move or RS failure in master cluster
> ------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-9465
>                 URL: https://issues.apache.org/jira/browse/HBASE-9465
>             Project: HBase
>          Issue Type: Bug
>          Components: regionserver, Replication
>            Reporter: Feng Honghua
>
> When region-move or RS failure occurs in master cluster, the hlog entries that are not pushed before region-move or RS-failure will be pushed by original RS(for region move) or another RS which takes over the remained hlog of dead RS(for RS failure), and the new entries for the same region(s) will be pushed by the RS which now serves the region(s), but they push the hlog entries of a same region concurrently without coordination.
> This treatment can possibly lead to data inconsistency between master and peer clusters:
> 1. there are put and then delete written to master cluster
> 2. due to region-move / RS-failure, they are pushed by different replication-source threads to peer cluster
> 3. if delete is pushed to peer cluster before put, and flush and major-compact occurs in peer cluster before put is pushed to peer cluster, the delete is collected and the put remains in peer cluster
> In this scenario, the put remains in peer cluster, but in master cluster the put is masked by the delete, hence data inconsistency between master and peer clusters

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