On Wed, 18 Jul 2007, Hannes Dorbath wrote:
On 18.07.2007 13:19, Justin Piszcz wrote:
For the HW RAID tests (2) at the bottom of the e-mail, no, I did not set
nr_requests or use the deadline scheduler.
For the SW RAID tests, I applied similar optimizations, I am probably not
at the latest firmware. The main thing I wanted to use though was SW RAID
because the card itself offers so many ports, however, with write speed
being that slow I am not sure its a good idea.
I think what you might be experiencing is that XFS can read su,sw values from
the MD device and will automatically optimize itself, while it can't do that
for the HW RAID device. It is absolutely essential to align your file system,
to prevent implicit reads, needed for parity calculations.
Set su to the stripe size you have configured in your controller (like 128K)
and sw to 9 (for a 10 disk RAID 5 array).
--
Regards,
Hannes Dorbath
Yes I agree here, but I guess my question is why is SW RAID5 so slow on
the 3ware card?
Justin.
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