[jira] [Reopened] (CASSANDRA-8193) Multi-DC parallel snapshot repair

["Yuki Morishita (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-8193?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Yuki Morishita reopened CASSANDRA-8193:
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JMX API should not use Cassandra specific class, as it can be used outside of Cassandra. I will attach patch to change API.

> Multi-DC parallel snapshot repair
> ---------------------------------
>
>                 Key: CASSANDRA-8193
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8193
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jimmy Mårdell
>            Assignee: Jimmy Mårdell
>            Priority: Minor
>             Fix For: 2.0.12, 2.1.3
>
>         Attachments: cassandra-2.0-8193-1.txt, cassandra-2.0-8193-2.txt
>
>
> The current behaviour of snapshot repair is to let one node at a time calculate a merkle tree. This is to ensure only one node at a time is doing the expensive calculation. The drawback is that it takes even longer time to do the merkle tree calculation.
> In a multi-DC setup, I think it would make more sense to have one node in each DC calculate the merkle tree at the same time. This would yield a significant improvement when you have many data centers.
> I'm not sure how relevant this is in 2.1, but I don't see us upgrading to 2.1 any time soon. Unless there is an obvious drawback that I'm missing, I'd like to implement this in the 2.0 branch.



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