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From Bryan Talbot <btal...@aeriagames.com>
Subject Re: SSTable size versus read performance
Date Thu, 16 May 2013 19:43:02 GMT
512 sectors for read-ahead.  Are your new fancy SSD drives using large
sectors?  If your read-ahead is really reading 512 x 4KB per random IO,
then that 2 MB per read seems like a lot of extra overhead.

-Bryan




On Thu, May 16, 2013 at 12:35 PM, Keith Wright <kwright@nanigans.com> wrote:

> We actually have it set to 512.  I have tried decreasing my SSTable size
> to 5 MB and changing the chunk size to 8 kb
>
> From: Igor <igor@4friends.od.ua>
> Reply-To: "user@cassandra.apache.org" <user@cassandra.apache.org>
> Date: Thursday, May 16, 2013 1:55 PM
>
> To: "user@cassandra.apache.org" <user@cassandra.apache.org>
> Subject: Re: SSTable size versus read performance
>
> My 5 cents: I'd check blockdev --getra for data drives - too high values
> for readahead (default to 256 for debian) can hurt read performance.
>
>

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