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From Jonathan Ellis <>
Subject Re: do I need to add more nodes? minor compaction eat all IO
Date Sun, 24 Jul 2011 00:04:37 GMT
On Sat, Jul 23, 2011 at 4:16 PM, Francois Richard <> wrote:
> My understanding is that during compaction cassandra does a lot of non sequential readsa
then dumps the results with a big sequential write.

Compaction reads and writes are both sequential, and 0.8 allows
setting a MB/s to cap compaction at.

As to the original question "do I need to add more machines" I'd say
that depends more on whether your application's SLA is met, than what
% io util spikes to.

Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support

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