[wplug] Hardware RAID tuning

[Max Putas]

Do you have the latest firmware on your controller? MegaRAID is known
to be a little wonky, and updates have fixed a few issues that I've
seen in the past.

On Wed, Jun 15, 2011 at 2:55 PM, Matthew Zwier <mczwier at gmail.com> wrote:
> Hi all,
>
> Thanks, Nate, Nicholas, ans Martin for your help.  I appear to be
> chasing Heisenbugs.  Today, all is much better.  I'm getting 250 MB/s
> sustained write speeds on my RAID 5s and 330 MB/s on my RAID 50.  I'm
> getting 250 MB/s sustained reads on my 7-disk RAID 5s and 320-400 MB/s
> on my 15 disk RAID 50 and RAID 5 respectively, as measured with dd and
> iotop.  Yesterday, the writes were topping out at 120 MB/s and the
> reads at 40 MB/s by any test I chose to run.  I ran some filesystem
> maintenence yesterday night, and the cluster is much more lightly
> loaded, but that's all that's changed.
>
> Today, xfsdump is fluctuating between 360 MB/s, 20 MB/s, and 875 kB/s,
> with the fluctuations correlating well with read accesses.  The
> filesystem I'm dumping is mounted but isn't in use, so it must be
> reads from other arrays on the same controller.  Could this be a
> poorly-configured disk scheduler?
>
> Seeing as how sequential performance isn't really the 40 MB/s that I
> feared, making this a problem with my backup idea instead of the RAID
> array itself, I think I'll be trying something other than xfsdump.
> rsync isn't the most palatable option (statting 37 million files takes
> a long time), but just about anything is better than a 5-day-long
> backup cycle.
>
> Thanks again,
> MZ
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-- 
Thanks,

Max Putas