[Beowulf] storage server hardware considerations

[Rahul Nabar]

On Wed, Jul 15, 2009 at 8:57 PM, Mark Hahn <hahn at mcmaster.ca> wrote:

> if you can't saturate gigabit with very modest raids,
> you're doing something wrong.  a single ultra-cheap disk
> these days (seagate 7200.12 500G, $60 or so) will hit close to 135 MB/s on
> outer tracks and average > 105 over
> the whole disk.  I'm guessing that you're losing performance
> due to either bad controllers (avoid HW raid on anything that's not fairly
> recent) or a combination of raid6 and a write-heavy workload...

Mark in a recent discussion recommends avoiding HW RAID. I am not
exactly sure what the caveat is about. Does this mean that software
RIAD under Linux outperform a dedicated RAID controllers?

I was speccing out a DAS box with a storage server. The storage server
had external RAID cards supposed to work with the SAS disks in the
box. Is this a config to be frowned upon?

Maybe I am misreading Mark's caveat. Any comments?

-- 
Rahul