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From Brandon Williams <dri...@gmail.com>
Subject Re: performance tuning - where does the slowness come from?
Date Thu, 06 May 2010 00:04:06 GMT
On Wed, May 5, 2010 at 6:59 PM, Mark Jones <MJones@imagehawk.com> wrote:

>  My data is single row/key to a 500 byte column and I’m reading ALL random
> keys (worst case read scenario)  Cache has minimal effectiveness, so the
> Bloom trees and indexes are getting a real work out.  I’m on 8GB Ubuntu 9.10
> boxes (64bit).  Yea, I was griping about the performance earlier, disk is
> heavily used by Cassandra, so outside of going to some highend SAS stuff,
> not sure what to do.
>

How many keys?  If your data size is exceeding your OS's cache capacity (8GB
- JVM size) then a completely random read pattern is mostly going to test
how fast your disk can seek.  You can try to use faster disks, but the
better solution is to add more nodes.

-Brandon

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