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

["Richard Low (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-5220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13969613#comment-13969613 ] 

Richard Low commented on CASSANDRA-5220:
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It's going to be a lot slower when there's little data because there is num_tokens times as much work to do. But when there is lots of data the times should be pretty much independent of num_tokens because most of repair is spent reading data and hashing. I ran some tests when we were developing vnodes (sorry, I don't have the data still available) and this was the case. Something might have regressed though.

> 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
>             Fix For: 2.1 beta2
>
>
> 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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