[jira] [Comment Edited] (CASSANDRA-5220) Repair improvements when using vnodes

["Ryan McGuire (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-5220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13971574#comment-13971574 ] 

Ryan McGuire edited comment on CASSANDRA-5220 at 4/16/14 4:05 PM:
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This is a yourkit comparison between the two runs of the dtest. Old Time is without vnodes, New Time is with vnodes. I turned off internode_compression because that run showed all the time being spent in Snappy compressor code, but even without compression the repair time didn't improve (much):

!5220-yourkit.png!


was (Author: enigmacurry):
I don't have a lot of experience with java profiling, but this is a yourkit comparison between the two runs of the dtest. Old Time is without vnodes, New Time is with vnodes. I turned off internode_compression because that run showed all the time being spent in Snappy compressor code, but even without compression the repair time didn't improve (much):

!5220-yourkit.png!

> Repair improvements when using vnodes
> -------------------------------------
>
>                 Key: CASSANDRA-5220
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5220
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>    Affects Versions: 1.2.0 beta 1
>            Reporter: Brandon Williams
>            Assignee: Yuki Morishita
>              Labels: performance, repair
>             Fix For: 2.1 beta2
>
>         Attachments: 5220-yourkit.png, 5220-yourkit.tar.bz2
>
>
> Currently when using vnodes, repair takes much longer to complete than without them.  This appears at least in part because it's using a session per range and processing them sequentially.  This generates a lot of log spam with vnodes, and while being gentler and lighter on hard disk deployments, ssd-based deployments would often prefer that repair be as fast as possible.



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