SmartArray 6i Preformance

[Matthew Kruer]

Smart Array 6i Performance

Server: HP DL380G4
Firmware: 2.84
Mode: Simplex
Cache: 192MB
Batteries: Yes
Array Accelerator: 50% Read / 50% Write
Drives: 6 x 146.8 SCSI Ultra320 15K.
RAID Configuration: 1+0
SCSI Mode: Simplex

In preparation for turning the server into a Xen box, I decided to do some extensive testing on the RAID array in various configurations the problem is not that I have not gotten it to work, but more that the expected performance is not what I was expecting.

It seems that all my writes are topped out at ~90MB/Sec write and 80MB/Sec Read while having the drives in RAID 1+0 configuration using all six drives. I also noticed that the burst read/write are topped out at ~175MB/Sec in all the testing I have done.

In theory the SCSI Ultra-320 should be able to provide 320 MB/s per channel, yet I am getting nowhere near those numbers. At the very least I would expect the burst rate to be closer to 320MB/s given the fact that I am using 6 drives.

I have been using the HDTune full 4.0 version. Is this normal?

I do have a SmartArray 642 card that I can use but I am not sure this will help. I can also configure the system as duplex, but this will also split drive array into 2/4 combo, and reading some posts here would degrade performance.

Also posted this question to StorageReview with pictures.
http://forums.storagereview.com/index.php/topic/28229-smart-array-6i-bottleneck/

Let me know if you need more info.

-Matt-

[Patrick Terlisten]

Hello Matt,

peformance is relative. ;) It depends on so much different parameters, like blocksize, chunksize of the array, queue depth etc.

What did you expect? 320 MB/s? I think the 175 MB/s are quite good for six "old" drives.

Regards,
Patrick

[Matthew Kruer]

Thatâ s why I was asking is because I donâ t know what to expect. When I did a simple RAID 1+0 on just two drives I had better MB/Sec bandwidth, but less IO. However with Six drives, the bandwidth dropped by about 10MB/sec but IO/sec marginally improved is some areas and got worse in others.

RAID 1+0 (2 drives)
Read: 100 MB/Sec
Write: 87 MB/Sec
Burst: 180 MB/Sec
IO Random Read 1MB: 57 IOPS
IO Random Write 1MB: 72 IOPS

RAID 1+0 (6 drives)
Read: 90 MB/Sec
Write: 80 MB/Sec
Burst: 175 MB/Sec
IO Random Read 1MB: 76 IOPS
IO Random Write 1MB: 86 IOPS

RAID 5 (6 drives)
Read: 70 MB/Sec
Write: 76 MB/Sec
Burst: 180 MB/Sec
IO Random Read 1MB: 83 IOPS
IO Random Write 1MB: 58 IOPS

In terms of an upper limit there does appear to be a cap at about 175-180MB/sec for the controller card. I donâ t expect doubling or tripling of the performance, but I would expect better the -10% on average read/write and +10% on IOPS

What this tells me is avoid RAID entirly if you can.