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DL380G5 poor disk performance

KJay
Occasional Visitor

DL380G5 poor disk performance

Our DL380G5 has the following specs:

10GB RAM
6x 10K SAS 146GB disks in RAID10 (3+3)
P400 256MB card with BBWC
All the F/W has been updated to the latest version as per requested by HP (bios, raid controller, hard drives etc)

This server just replaced our DB2 server which was hosted on very old DL380 G3.

The old server spec:

3GB RAM
6x 10K SCSI 146GB disks in RAID10 (3+3)
Smart Array 5i 64MB card with NO BBWC


The same DB2 SQL query takes 5-6 times longer on the new server and I suspect this is due to bad disk performance on the new server.

Test results using "hdparm -tT"

New server:
/dev/mapper/VolGroup00-root_lv:
Timing cached reads: 234 MB in 2.00 seconds = 116.93 MB/sec
Timing buffered disk reads: 130 MB in 3.01 seconds = 43.12 MB/sec

Old server:
/dev/mapper/VolGroup00-root_lv:
Timing cached reads: 1366 MB in 2.00 seconds = 682.60 MB/sec
Timing buffered disk reads: 178 MB in 3.01 seconds = 59.17 MB/sec

1) As you can see the cache reading performance is really bad on the new server.

2) I expected much better output from RAID 10 drives from both drive on buffered disk reads but again the new server is much worse.

The O/S is CentOS 5.5 with the latest kernel (64bit on the new server).

I've been dealing with HP support but not much luck. The L2 engineer said the disk performance is acceptable for the current setup.

Any help will be very appreciated.

Regards,
Jay
5 REPLIES
Johan Guldmyr
Honored Contributor

Re: DL380G5 poor disk performance

Hdparm is only meant to be used on single ATA drives. Maybe you can compare with another tool? Does iometer work in this scenario?

What are your controller settings (as seen in ACU)? Like stripe size, read/write cache ratio etc.

What about file system configurations, anything special there?

Re: DL380G5 poor disk performance

Johan,

Very good questions. I like it. :)
Kind Regards,
Erdogan.
I am HPE Employee

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Johan Guldmyr
Honored Contributor

Re: DL380G5 poor disk performance

It's only questions but maybe it will lead us to figuring out how to improve performance. Or if it's possible. I don't have the hardware so can't tell you what my rates are. But.

First thing on any performance investigation tough is to get a valid baseline.

Please check out http://sourceforge.net/projects/iometer/
Michael A. McKenney
Respected Contributor

Re: DL380G5 poor disk performance

Upgrade firmware on drives and controllers. Add a battery to enable the caching. No battery disables most caching features on a RAID controller.
Johan Guldmyr
Honored Contributor

Re: DL380G5 poor disk performance

Michael: it's on the old (faster?) server that they don't have BBWC on.

But drivers is a good idea.

I hope you're not using some kind of default drivers in CentOS?