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From Carl Lerche>
Subject Re: How often to run `nodetool repair`
Date Thu, 01 Aug 2013 19:03:55 GMT

Yes, my use case for this Cassandra cluster is analytics. I am building a
google dapper (application tracing) like system. I collect application
traces and write them to Cassandra. Then, I have periodic rollup tasks that
read the data, do some summarization and write it back.

Thoughts on how to manage a write heavy cluster?


On Thu, Aug 1, 2013 at 11:28 AM, Arthur Zubarev <>wrote:

>   Hi Carl,
> The ‘repair’ is for data reads. Compaction will take care of the expired
> data.
> The fact a repair runs long makes me think the nodes receive unbalanced
> amounts of writes rather.
> Regards,
> Arthur
>  *From:* Carl Lerche <>
> *Sent:* Thursday, August 01, 2013 12:35 PM
> *To:*
> *Subject:* How often to run `nodetool repair`
>  Hello,
> I read in the docs that `nodetool repair` should be regularly run unless
> no delete is ever performed. In my app, I never delete, but I heavily use
> the ttl feature. Should repair still be run regularly? Also, does repair
> take less time if it is run regularly? If not, is there a way to
> incrementally run it? It seems that when I do run repair, it takes a long
> time and causes high amounts CPU usage and iowait.
> Thoughts?
> Thanks,
> Carl

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