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https://issues.apache.org/jira/browse/HBASE-19024?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16403324#comment-16403324
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Anoop Sam John commented on HBASE-19024:
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setForceSync - to be forceSync ? 
isForceSync - Not used. Do we need this? I can not see even in tests been used. 
So we can enable hsync over hflush at server level by hbase.wal.hsync new 
config. And individually a Mutation can mark any lower Durability also. Same 
way even if this config is NOT ON at RS level, still Mutation can mark so. 
Correct?
In case of AsyncFSWAL, we do not use this new config and seems we use only 
hflush way there.(Offline confirmed with [~Apache9]).   Another issue to fix 
that or in this issue only?

> provide a configurable option to hsync WAL edits to the disk for better 
> durability
> ----------------------------------------------------------------------------------
>
>                 Key: HBASE-19024
>                 URL: https://issues.apache.org/jira/browse/HBASE-19024
>             Project: HBase
>          Issue Type: Improvement
>          Components: wal
>         Environment: 
>            Reporter: Vikas Vishwakarma
>            Assignee: Harshal Jain
>            Priority: Critical
>             Fix For: 3.0.0, 2.1.0, 1.5.0
>
>         Attachments: HBASE-19024-master.v10.patch, 
> HBASE-19024.branch-1.2.001.patch, HBASE-19024.branch-1.2.002.patch, 
> HBASE-19024.branch-1.2.003.patch, HBASE-19024.branch-1.2.004.patch, 
> HBASE-19024.branch-1.2.005.patch, branch-1.branch-1.patch, 
> branch-1.v1.branch-1.patch, master.patch, master.v2.patch, master.v3.patch, 
> master.v5.patch, master.v5.patch, master.v6.patch, master.v9.patch
>
>
> At present we do not have an option to hsync WAL edits to the disk for better 
> durability. In our local tests we see 10-15% latency impact of using hsync 
> instead of hflush which is not very high.  
> We should have a configurable option to hysnc WAL edits instead of just 
> sync/hflush which will call the corresponding API on the hadoop side. 
> Currently HBase handles both SYNC_WAL and FSYNC_WAL as the same calling 
> FSDataOutputStream sync/hflush on the hadoop side. This can be modified to 
> let FSYNC_WAL call hsync on the hadoop side instead of sync/hflush. We can 
> keep the default value to sync as the current behavior and hsync can be 
> enabled based on explicit configuration.



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