ML310 G5p RAID / Tape performance

[Bill Pedersen]

I am trying to understand the difference in performance between the HP Embedded RAID controller and the LSI SAS HBA RAID controller.

I also need to then have an understanding of whether the use of the Embedded RAID controller would then improve the backup performance to an Ultrium 920 connected to the LSI SAS HBA.

I currently have the RAID on the HBA as well as the tape. Backup is really not what I would consider optimal. The tape does not seem to ever get into streaming mode and the throughput ends up around 500 MB per minute or less.

The server is running Win SBS 2008 and has 4 GB of memory.

If the Embedded RAID controller has sufficient performance in comparison to the LSI SAS HBA and I can get better backup performance then I could see reconfiguring the server. But if I can not get any better performance I will just leave it alone.

On the basis of queuing and independent operation of controllers I would expect to get better performance by moving the drives. But I have no specific experience with this configuration and am looking for some information from those with more experience.

Thanks,

Bill.

[Johan Guldmyr]

Hi,

initially my response would be that you would need another HBA for the disks. Preferbly a HBA with a BBWC (battery backed write-cache) and then have the tape drive alone on the LSI SAS HBA.

I doubt that the embedded raid controller is good enough for this.

Also how many disks do you have in the system?
Raid1? Raid5? What kind of disks? That can also have a significant impact on the performance.

So 500MB/minute is around 8.3MB/s. I believe the Ultrium 920 needs a lot faster data input than that to be optimal.

For the Ultrium 920 the "Data rate matching range" is 20-60 MB/s (native).
Which means that you need at the absolute minimum 20MB/s for it to not stop/rewind the tape all the time.

Saw a little more info here:
"http://forums.storagereview.net/index.php?showtopic=25656&mode=threaded&pid=243908"

And here:
http://www.hp.com/products1/storage/compatibility/tapebackup/ISS/Detail/16-0038-0147.html

This lists the recommended HBA for the Ultrium 920 SAS.

This could possibly have something to do as well with the media you are using, if they are now too worn, they will get slower and slower.

If you haven't installed Library and Tape Tools yet, I would recommend doing so and running the LTO Drive Assessment test.

[Bill Pedersen]

Johan:

Thanks for responding.

The LSI HBA is actually what HP Calls their SC44Ge HBA so it is the recommended HBA. This HBA is SAS and also handles SATA drives.

The drives are the HP 250GB 3G SATA Hot Plug 7,200rpm 3.5" MDL Hard Drives.

Both RAID controllers support only RAID0 and RAID1, nothing more, although they both support hot spares as well.

Am using the HP Data Protector Express Software which came with the drive.

You mention the Library and Tape Tools where can I find this?

Thanks,

Bill.

[Johan Guldmyr]

Heya,

http://h20000.www2.hp.com/bizsupport/TechSupport/DriverDownload.jsp?prodNameId=406731〈=en&cc=us&taskId=135&prodSeriesId=406729&prodTypeId=12169

Is the link to LTT.

Tried to find out how much performance one can expect from one SATA drive in terms of MB/s but couldn't find that :/

Only the IOPS .. http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c01671044 which would indicate that RAID1 is the best option, compared to RAID5.

[Bill Pedersen]

Thanks for link.

The description of the SAS HBA suggests 1.5Gb/S... or about 200 MB/Sec assuming the mean bit and not Bytes by the use of the "b".

HP SC44Ge Host Bus Adapter
NOTE: RAID 0, 1.
NOTE: When using the SC44Ge with SATA Hard Drives, 1.5G SATA Hard Drives are required. Transfer rate: 1.5 Gb/s SATA, 3 Gb/s SAS 416096-B21

But the drive descriptions suggests 3Gb/sec:

HP 250GB 3G SATA Hot Plug 7,200rpm 3.5" MDL Hard Drive

So this suggests a 3 Gb/s interface...

So I guess I will need to consider doing some experimenting...

Thanks!

Bill.

[Johan Guldmyr]

The SATA drives will go down to 3Gbps (3 giga bit per second) with that card. The SATA drives won't surpass 150MB anytime soon.

Please experiment ahead, keep me updated if you want :)

[Bill Pedersen]

Johan:

Yes, I checked and the SAS controller down grades the SATA drives from 3 Gb/s to 1.5 Gb/s...

Current throughput is about 5MB/s to as HIGH as 11 MB/s, not really where I would like to see it. I will investigate reconfiguring for now with the Embedded SATA controller an see if that gives any better performance on the backups.

Thanks,

Bill.

[Bill Pedersen]

Well, for right now it does not make a difference. HP in their wisdom did not send the wiring harnress to attached to the embedded SATA controller!

So, until I can dig one up experimentation is on hold.