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From Peter Schuller <>
Subject Re: keycache persisted to disk ?
Date Mon, 13 Feb 2012 09:15:54 GMT
> 2 Node cluster, 7.9GB of ram (ec2 m1.large)
> RF=2
> 11GB per node
> Quorum reads
> 122 million keys
> heap size is 1867M (default from the AMI I am running)
> I'm reading about 900k keys

Ok, so basically a very significant portion of the data fits in page
cache, but not all.

> As I was just going through cfstats - I noticed something I don't understand
>                 Key cache capacity: 906897
>                 Key cache size: 906897
> I set the key cache to 2million, it's somehow got to a rather odd number

You're on 1.0 +? Nowadays there is code to actively make caches
smaller if Cassandra detects that you seem to be running low on heap.
Watch cassandra.log for messages to that effect (don't remember the
exact message right now).

/ Peter Schuller (@scode,

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