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From Oskar Kjellin <oskar.kjel...@gmail.com>
Subject Re: Downside to running multiple nodetool repairs at the same time?
Date Sat, 22 Apr 2017 07:22:23 GMT
Yes I really think you should consider this Eugene. Triggering on all replicas at the same
time will increase your latencies noticeably. 


> On 21 Apr 2017, at 22:25, Jon Haddad <jonathan.haddad@gmail.com> wrote:
> 
> We (The Last Pickle) forked reaper a while ago and added support for 3.0.
> 
> https://github.com/thelastpickle/cassandra-reaper
> 
> We set up a mailing list here for Reaper specific questions: https://groups.google.com/forum/#!forum/tlp-apache-cassandra-reaper-users
> 
> Jon
> 
>> On Apr 21, 2017, at 1:11 PM, eugene miretsky <eugene.miretsky@gmail.com> wrote:
>> 
>> The Spotify repo (https://github.com/spotify/cassandra-reaper) seems to not be maintained
anymore. I'm not sure if they even support Cassandra 3.0 (https://github.com/spotify/cassandra-reaper/issues/140).

>> 
>> Regardless, in Cassandra 3.0 repairs are
>> 1) Incremental, which means that the same SSTables will not be repaired twice. 
>> 2) Parallel, which means that when you call repair, all nodes repair at the same
time. 
>> 
>> I suppose that in the worst case, calling repair from X nodes could trigger X repair
processes (that will each trigger a Markel tree building on each node). But I would assume
that Cassandra prevents this by making sure that there is only one repair process running
per node. 
>> 
>> 
>> 
>>> On Fri, Apr 21, 2017 at 2:43 AM, Oskar Kjellin <oskar.kjellin@gmail.com>
wrote:
>>> It will create more overhead on your cluster. Consider using something like reaper
to manage.
>>> 
>>> > On 21 Apr 2017, at 00:57, eugene miretsky <eugene.miretsky@gmail.com>
wrote:
>>> >
>>> > In Cassandra 3.0 the default nodetool repair behaviour is incremental and
parallel.
>>> > Is there a downside to triggering repair from multiple nodes at the same
time?
>>> >
>>> > Basically, instead of scheduling a cron job on one node to run repair, I
want to schedule the job on every node (this way, I don't have to worry about repair if the
one node goes down). Alternatively, I could build a smarter solution for HA repair jobs, but
that seems like an overkill.
>> 
> 

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