We are running with Async IO right now, it's yielding better results
with multipath.

On Apr 24, 5:06 pm, Konrad Rzeszutek <kon...@virtualiron.com> wrote:
> On Fri, Apr 24, 2009 at 02:14:43PM -0400, Donald Williams wrote:
> > Have you tried increasing the disk readahead value?
> > #blockdev --setra X /dev/<multipath device>
>
> >  The default is 256.    Use --getra to see current setting.
>
> >  Setting it too high will probably hurt your database performance.  Since
> > databases tend to be random, not sequential.
>
> I would think that the databases would open the disks with O_DIRECT
> bypassing the block cache (And hence the disk readahead value isn't used
> at all).
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