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From Tyler Hobbs <>
Subject Re: Cassandra and disk space
Date Thu, 09 Dec 2010 17:56:07 GMT
If you are on 0.6, repair is particularly dangerous with respect to disk
space usage.  If your replica is sufficiently out of sync, you can triple
your disk usage pretty easily.  This has been improved in 0.7, so repairs
should use about half as much disk space, on average.

In general, yes, keep your nodes under 50% disk usage at all times.  Any of:
compaction, cleanup, snapshotting, repair, or bootstrapping (the latter two
are improved in 0.7) can double your disk usage temporarily.

You should plan to add more disk space or add nodes when you get close to
this limit.  Once you go over 50%, it's more difficult to add nodes, at
least in 0.6.

- Tyler

On Thu, Dec 9, 2010 at 11:19 AM, Mark <> wrote:

> I recently ran into a problem during a repair operation where my nodes
> completely ran out of space and my whole cluster was... well, clusterfucked.
> I want to make sure how to prevent this problem in the future.
> Should I make sure that at all times every node is under 50% of its disk
> space? Are there any normal day-to-day operations that would cause the any
> one node to double in size that I should be aware of? If on or more nodes to
> surpass the 50% mark, what should I plan to do?
> Thanks for any advice

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