Scott Marlowe schrieb:
On Wed, Dec 10, 2008 at 12:45 AM, Mario Weilguni <mweilguni@xxxxxxxx> wrote:
A customer of us uses the P400 on a different machine, 8 SAS drives (Raid 5
as well), and the performance is very, very good. So we thought it's a good
choice. Maybe the SATA drives are the root of this problem?
What tests have you or the customer done to confirm that performance
is very very good? A lot of times the system is not as fast as the
customer thinks, it's just faster than it was before and they're
happy. Also, there could be problems in the driver or firmware on
your P400 versus the customer one. I'd look for those differences as
well. I doubt SATA versus SAS is the problem, but who knows...
Well, I cannot take the box offline to make usefull tests like tiobench
or bonnie, but even with the current service running I get from a simple
dd between 270 and 340 MB/sec sustained read over 30% of the disk.
It also performed extremly good when I put the box into production,
pg_bench values were impressing, but I do not have them at hand.
However, currently we are seriously considering dropping RAID5 in favor
of RAID10, we will test this week if this performs better.
Regards
Mario
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