Re: RAID Controller (HP P400) beat by SW-RAID?

>From: pgsql-performance-owner@postgresql.org
[mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Anthony Presley
>Sent: Sunday, September 11, 2011 4:45 PM
>To: pgsql-performance@postgresql.org
>Subject: [PERFORM] RAID Controller (HP P400) beat by SW-RAID?

>We've currently got PG 8.4.4 running on a whitebox hardware set up, with
(2) 5410 Xeon's, and 16GB of RAM.  It's also got (4) 7200RPM SATA drives,
using the onboard IDE controller and ext3.

>A few weeks back, we purchased two refurb'd HP DL360's G5's, and were
hoping to set them up with PG 9.0.2, running replicated.  These machines
have (2) 5410 Xeon's, 36GB of RAM, (6) 10k SAS drives, and are using the HP
SA P400i with 512MB of BBWC.  PG is running on an ext4 (noatime) partition,
and they drives configured as RAID 1+0 (seems with this controller, I cannot
do JBOD).  I've spent a few hours going back and forth benchmarking the new
systems, and have set up the DWC, and the accelerator cache using hpacucli.
 I've tried accelerator caches of 25/75, 50/50, and 75/25.
>

I would start of by recommending a more current version of 9.0...like 9.0.4
since you are building a new box. The rumor mill says 9.0.5 and 9.1.0 might
be out soon (days?). but that is just rumor mill. Don't bank on it.

What kernel are you on ?

Long time HP user here, for better and worse... so here are a few other
little things I recommend.

Check the bios power management. Make sure it is set where you want it.
(IIRC the G5s have this, I know G6s and G7s do). This can help with nasty
latency problems if the box has been idle for a while then needs to start
doing work.

The p400i is not a great card, compared to more modern one, but you should
be able to beat the old setup with what you have. Faster clocked cpu's more
spindles, faster RPM spindles.

Assuming the battery is working, with XFS or ext4 you can use nobarrier
mount option and you should see some improvement.

Make sure the raid card's firmware is current. I can't stress this enough.
HP fixed a nasty bug with Raid 1+0 a few months ago where you could eat your
data... They also seem to be fixing a lot of other bugs along the way as
well. So do yourself a big favor and make sure that firmware is current. It
might just head off headache down the road.

Also make sure you have a 8.10.? (IIRC the version number right) or better
version of hpacucli... there have been some fixes to that utility as well.
IIRC most of the fixes in this have been around recognizing newere cards
(812s and 410s) but some interface bugs have been fixed as well.   You may
need new packages for HP health. (I don't recall the official name, but new
versions if hpacucli might not play well with old versions of hp health.

Its HP so they have a new version about every month for firmware and their
cli utility... that’s HP for us.

Anyways that is my fast input.

Best of luck,