Slow backups to LTO1 and LTO2

[dpoulson]

Hi,

I'm currently having some speed issues with our backups using NetBackup (4.5GA).

To both LTO 1 drives (with LTO1 tapes) and LTO 2 drives (with LTO 2 tapes) I'm getting an average of about 5Mb/sec being backed up.

I'm backing up from storage directly attached to the master server/media server (HDS 9970 disk array through brocade switches/SAN) to tape drives also attached to the same server. i.e. no network involved.

There are 4 LTO 1 drives and 4 LTO 2 drives (all in a single L180), each group of 4 running as a seperate storage unit.

Any ideas where the bottleneck could be. From what I've read I should be getting at least 15Mb/s, up to 30Mb/s with the LTO 2's. Any more information needed, just ask.

Cheers,

Darren.

 

[comtec17]

This would depend what type of files you are backing up and their sizes. If you are backing up a ton of small files like on a C:\ drive, your speed is not going to be all that great.

The max rated speed for these drives is if you are in a perfect, clean environment. Some of the items you can do to try to improve your performance is setting some buffers.

 

[dpoulson]

Some of the areas will have large amounts of small files, but the main area that is getting backed up is an oracle database partition full of a small amount of large files (50 files, about 80Gb) and is taking about 4.5 hours to send to tape.

The disks are connected to the server with dual 2gb fibre, and the tape drives are connected with ultra-320 scsi cards (LSI).

How would I go about setting any buffers (or more to the point, and links to documents for tuning?)

Cheers,

Darren

 

[comtec17]

faq776-5985

 

[dpoulson]

Cheers for that, got it working now. I had adjusted the buffers before but the backups stopped working. Looks like the key was shared memory. I set the shared memory to 4.5Gb, and the buffer size to the recommended for LTO's (262144) and now my backups are going at about 20Mb/s

Thanks,

Darren.

 

[daFranze]

had a similar problem, very slow backups of the Windows Clients but fast Backup of the UNIX Clients.

Solution: the Windows Cliets had a Virus Scan enabled during read; we disabled the Viruscheck and the Backups are as fast as the UNIX Backups...

Best Regards, Franz
--
Solaris System Manager from Munich, Germany
I used to work for Sun Microsystems Support (EMEA) for 5 years in the domain of the OS, Backup and Storage