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Slow DLT drives

Randy Lowe
Occasional Contributor

Slow DLT drives

We run a nightly backup on a DLT 7000 attached to an HP 9000 running HP-UX 11.11. We are running Openview Omniback II 3.5.to initiate the backups.The DLT 7000 has four drives. Drive devices DLT1 and DLT2 backup 18 filesystems with 9 of these 18 approx 9.7 GB in size. The problem is with the other drive devices DLT3 and DLT4.
Why can't these two other drives backup 7 filesystems with 6 of these approx. 9.7 GB in size in less time as DLT1 and DLT2 complete 18
filesystems with 9 at 9.7 GB?
They start at the same time but DLT1 and DLT2 finish way before DLT3 and DLT4 backups.
Any ideas?
Only two things wrong with women, everything they say and everything they do.
3 REPLIES
Eugeny Brychkov
Honored Contributor

Re: Slow DLT drives

Randy,
to be sure about drives' health check them with HP LTT http://www.hp.com/cposupport/information_storage/support_doc/lpg50128.html . If you wish you can zip support tickets for them and attach to your next reply.
In your case problem may be in block size. Please do not use 2K block size, set it up to at least 8K. Try playing with it to see how backup time changes
Eugeny
Leif Halvarsson_2
Honored Contributor

Re: Slow DLT drives

Hi,
Is it the same kind of data on all filesystems (filesizes, number of files) ?
Is the disk systems for all filesystems aq about equal performance ?
Is all drives connected to their own SCSI bus ?
Is there perhaps any network bottleneck (I don't know if all filesystem is on one server or not).

Re: Slow DLT drives

Is it possible that you can swap the jobs running on DLT1 & 2 with DLT's 3 & 4. This will help narrow down the cause of the differential