Backup very slow to IBM HH Gen 3 LTO drive... 27mb/minute!

[higherorbit]

G'day

I've got an IBM SystemX 3650, attached via SAS to an external IBM half height LTO 3 drive (IBM #43W8478)

Getting very slow backup rates, the fastest thus far is 27mb per MINUTE. This is absurdly slow. This occurs with different tapes.

Just to test I set up a B2D job with the same selection list, and the job rate was as expected.

This leads me to think either the drive is faulty (IBM's tape drive utility say otherwise), the drivers are playing up, or the Symantec drivers aren't working right..

The LTO3 drive has the latest firmware and system drivers, as well as the SAS adapter (which is an IBM HBA SAS, IBM# 25R8060).

Any ideas?

Cheers
Steve

[Ben_L_]

Well to rule out a driver problem, load the vendor drivers for the tape drives and run the backup again.  Backup Exec does not require the Symantec drivers, they are just recomended. 

[higherorbit]

I was able to get a much faster backup rate, of around 400mb/min (over the network) by increasing the block and buffer size on the drive, via the drive properties in BE. However, once the BE services are restarted (from either a system reboot or manual restart of services), the adjusted block and buffer sizes are no longer retained, and revert back to default.

What is going on?

[higherorbit]

Just upgraded the BE11d to BE 12, and now it says my drive is not supported at all!! Am yet to reboot to find out... !!!!

[osmik]

Hello,

Have you solved your problem yet?

I'm facing the same problem on the same hardware.....
I'going to open support case with IBM support, because this problem (in my opinion) doesn't relate do Bexec.

I tried to backup data using ntbackup, with the same results (backups at about 26 MB/min!).

[higherorbit]

Hi Osmik,

50% solved. Can get backups running fine with the adjusted block/buffer sizes as described in my post above, but still need to manually adjust those sizes after every reboot or every time the BackupExec services are restarted.

Have been getting excellent transfer rates, but it is a case of remembering to adjust them after every restart. As you can imagine it is a bit of a pain.

[melps]

Hi higherorbit,

Can you post your final config for block/buffer size and the resultant thruput.

Thanks for your help.

[higherorbit]

Melps,

Average about 1000-1300MB per minute, buffer is set to 1mb, and I have been experimenting with block size of 64kb and 256kb. 64kb gives the speed as stated, 256kb bumps it up another 300-400mb per minute.

I have run verifies on the higher block size and they have checked out okay, but haven't actually restored data. From what I've read having a larger block size can compromise some backups.

Also the system is now retaining my device settings after reboots.

BEWS 12
Service Pack 1
Hotfix 300831
Hotfix 302981

Good luck!