On 13/12/06 12:18 AM, "Adrian Saul" <asaul AT HOME-BOX.ODS DOT ORG> wrote:

> If you are using RAID-3 make sure you have only a single stream reading
> from the device - otherwise you will kill the performance.
> 
> For a reason no-one can find documented, we have multiple 2Tb Clariion
> devices which we found to be RAID-3 5400rpm ATA disks (setup before our
> time).  Single stream performance is great and we can get it up to
> around 90Mb/s on benchmarks, but they are configured with two AFT
> devices each so when the staging kicks off we get about 30Mb/s total
> performance from each RAID device.  Our poor LTO-2s are sitting there
> performing at half speed all day....  Because of that we end up with a
> stage that takes 18 hours in a 12 hour window.

The 5400RPM ATA CLARiiON disks/LUNs offered considerably lower performance
than desired for disk backups, and every site I saw experienced similar
problems. It would seem however that the more recent SATA enclosures have
provided better performance.

Cheers,

Preston.

-- 
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