ML370G3 SCSI Disk Performance vs XP Pro Client IDE Drive

[Craig W]

There may be a straightforward answer to this Q., however it has me puzzled as I would have thought Ultra320 SCSI 10K disk performance would outdo a slower 7,200 ATA-133 drive.

I have traced a slow server Database application to a disk write bottleneck on the following system: ML370G4 Windows 2003 Server, with 3.6Ghz Xeon, 1GB RAM, 642 Smart Array Controller and 2x 146.8-GB Plugable Ultra320 SCSI 10,000 rpm Hard Drives.

I originally had the disks set-up in RAID 1+0 however for the purposes of testing, and to eliminate the array factor from the equation, I converted to single RAID 0, 128KB (default) Stripe disk.

The slow performance only occurs during one command in the Database application (Posting operation that takes newly entered orders and changes their status flag from 'E' to 'O'pen Orders). Its taking ~10 minutes to complete for RAID 1+0, and ~8.5 minutes for the RAID 0. From what I can see the function involves continuous sustained writing to the disk for the majority of the 'posting' time. The post shouldn’t take more than 1 to 2 minutes.

I have done numerous tests using Windows perfmon on the ML370, and compared the results to a stand-alone Windows XP Pro system, with 1.5Ghz P4, 256MB RAM, Samsung 80GB 7,200 ATA-133 Drive. The same application software set-up was employed on both systems.

The DB Application is designed to run over the LAN, however for the server performance tests I have run the application direct on the server console. From the numerous recorded parameters collected I believe the relevant ones are the Disk Writes/s, Bytes/s, and Disk %Time (Processor, Memory, and other resource thresholds are low).

ML370G4 Server:
Disk Writes/s = ~200
Bytes/s = ~900K
Disk %Time = ~98%
DB Post Time = ~8.5min

P4 System:
Disk Writes/s = ~790
Bytes/s = ~3000K
Disk %Time = ~30%
DB Post Time = 2.5min

As can be seen the P4 System is writing to disk at least 3x the speed of the ML370.

The P4 System's 7,200rpm IDE dive has a max. host to drive buffer transfer rate of 133MB/s and the ML370's 10K rpm SCSI has a max.rate of 320MB/s.

What is occurring here, shouldn’t the Ultra320SCSI + 642 Smart Controller combination be producing better performance than this, esp. compared to the less resourceful P4 System?

At less than 1MB/s transfer rate it seems the 320MB/s rated SCSI isn’t being used to capacity, however the Disk %Time indicates max.usage.

Can anyone please shed some more experienced light on this and suggest a possible solution.

Thanks, Craig.W

[Craig W]

My appologies the Subject line should have shown a ML370G4 and not G3 server.

[Craig W]

Are there any HP Engineers monitoring this forum that could offer some technical advice on this?

[Craig W]

For information that may assist others please see the thread at:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=982553&admit=-682735245+1134890899191+28353475