Server Performance

Hi

Been having interesting times with an IBM x3650 with 8 15k RPM 73GB drives
in RAID 10 and a ServRAID 8K controller with Write-Back cache enabled
(battery installed and working). Currently getting a pgbench score of 4.7
transactions per second! After playing with the postgresql configuration
file, I'm certain that this is not a postgresql problem. I have tried two
different Linux distro's upon the server both with the same problems. I'm
fairly certain that this is a problem with the hardware configuration /
setup, however I'm still waiting for IBM to contact me!

Initially I started with the OS on a RAID 1 array and a 6 drive RAID 10
array for postgresql. With this setup I got 3tps, altering the RAID
configuration to a single 8 drive array, running both the OS and
postgresql. I was able to reach 700tps, however after upgrading to the
latest RAID controller firmware this has now fallen back to 4tps.

Benchmarking another server I have access to, 4 15k 73GB RPM disks with a
Dell Perc 5/i controller. I consistently get a pgbench score of 1400tps.
Therefore taking a linear extrapolation I expect the IBM x3650 to manage
~3000tps. Additionally my Laptop with a 5400 RPM sata disk was able to
score ~200tps.

I have two of these IBM x3650's running the following configurations:

1) IBM x3650
IBM ServRAID controller (Rebranded Adaptec card, using the aacraid
driver)
2 15k RPM 73GB RAID 1 (OS array)
6 15k RPM 73GB RAID 10 (Postgresql data array)
2 quad core 3.0GHz Intel Xeons
8 GB ram
SuSE Linux Enterprise Server 10 (2.6.16 kernel)
Postgresql 8.3.4 (compiled from source)

2)
IBM x3650
IBM ServRaid controller (Rebranded Adaptec card, using the aacraid
driver)
8 15k RPM 73GB RAID 10 (OS and Postgres data array)
2 quad core 3.0GHz Intel Xeons
8 GB ram
Mandriva 2009 Free (2.6.27.19 kernel)
Postgresql 8.3.7

As I said, I have the same problem on both machines, I'm expecting that
this is caused by the low quality RAID controllers IBM has floged us.

I'm interested to find out whether any one out there has had similar
problems with IBM ServRAID controllers, or IBM hardware in general?

What SAS RAID controllers are people using?

What RAID configurations are people using?

What SAS RAID controllers would anyone recommend purchasing?

Any information is gratefully received

Chris Ellis
Shropshire Council
chris(dot)ellis(at)shropshire(dot)gov(dot)uk

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