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https://issues.apache.org/jira/browse/CASSANDRA-10070?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15045293#comment-15045293
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Russell Bradberry commented on CASSANDRA-10070:
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While it may intuitively seem like you want to kick-off a repair as soon as a
node comes back online, it can be very dangerous in a production environment.
Starting the most resource intensive process on a node that is already
problematic, in a cluster that is already having issues can exacerbate the
issue and lead to a longer outage, or degradation, than anticipated.
Network reliability is also another aspect of this. Lets say you have 3 nodes,
RF=3 and there is a partition dividing node A and node B. All nodes are still
actually, up, but in this case node A will start a repair on B and B will start
a repair on A. Now 2/3 of your cluster is un-needly repairing which can cause
serious performance problems, especially when running a loaded cluster.
Also:
Other times you might not want a repair automatically started:
- The cluster is in the middle of a rolling upgrade where streaming is broken
between versions.
- Heavily loaded clusters during normal operation (some users schedule repairs
at night to not affect performance during normal hours of operation)
- Clusters where the read-consistency is high enough to account for the hints
beyond the window allowing the user to schedule the repair for a time that
makes sense for their cluster and use-case.
> Automatic repair scheduling
> ---------------------------
>
> Key: CASSANDRA-10070
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10070
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Marcus Olsson
> Assignee: Marcus Olsson
> Priority: Minor
> Fix For: 3.x
>
>
> Scheduling and running repairs in a Cassandra cluster is most often a
> required task, but this can both be hard for new users and it also requires a
> bit of manual configuration. There are good tools out there that can be used
> to simplify things, but wouldn't this be a good feature to have inside of
> Cassandra? To automatically schedule and run repairs, so that when you start
> up your cluster it basically maintains itself in terms of normal
> anti-entropy, with the possibility for manual configuration.
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