Very Slow with Storageworks DLT VS80 and Backup Exec 8.6

[David Richards_3]

I have a new installation of Backup Exec 8.6 and a HP branded "Storageworks DLT VS 80 External".

When I try to back up my server locally (30gb) it takes over 24 hours and give me a data rate of less than 8 megabyte per minute.

Using Windows built in Backup tool it is also just as slow.

Server: Compaq Proliant ML 350 Generation 2 with an external SCSI port using Channel 0 on the Internal SCSI controller. Nothing else on the SCSI port (or card for that matter).


Veritas Backup Exec Support can't figure it out either.

[CA713937]

> data rate of less than 8 megabyte per minute.

That's really bad. You should be able to get 3MB/sec (not minute) out of the drive if you can stream it.

The 350G2 had an integrated Ultra3 controller, which should be a good match.

The tape compatability matrix only lists the 350G3, but there is no technical reason the 350G2 should not work with this drive (it may not have been specifically tested). Here's the matrix:
http://www.hp.com/products1/storage/compatibility/tapebackup/proliant/index.html

Technically, if the internal SCSI is not listed as supported (i.e. tested), the recommendation is usually to use a dedicated HBA (like an adaptec 29160). However, I don't think that's your problem.

Are you backing up across a 10/100Mb network or backing up many very small files?

Is your block size 64K or better?

Look at this performance troubleshooting page:
http://h20015.www2.hp.com/hub_search/document.jhtml?lc=en&docName=lpg50167

And the performance tools page:
http://www.hp.com/support/pat

[Harry Lubansky]

I have installed a new Compaq ML370 G3 with the same VS80 tape drive. I saw the same slow performance, approx 5Mb/ min, with the first backup I made on the server, took over 50 hrs. I replaced the drive with the previous tape drive from the old ML 530 server, a SDLT-9000 DAT DDS3 format. That tape drive, with the same SCSI cable and port on the server, backed up at 50 Mb/min. I am in the process of contacting Compaq support for help myself.

[CA713937]

Harry,

Can you run the performance tools on your vs80 tape drive with the tape that had the slow performance?

If you install HP Library & Tape Tools (www.hp.com/support/tapetools) it has the performance tests built-in.

[CA713937]

David,

Any updates on your problem? This shouldn't be too hard to find root cause (knock on wood).

[David Richards_3]

Hi David,

Thanks for your suggestions... Here's what I found:

The Block Size in Backup Exec was set to 32K. When I pressed "Default settings" it bumped it down to 1K. Vertias said that's because I am using the wrong tape drivers (HP's driver and not Veritas).

So I manually bumped up the Block size to 64K and ran a small (2 gb) test back up. I got about 130mb/min.

[David Richards_3]

... continued...

Tomorrow I will run a "real" backup of about 30gb and see what kind of rate I get and post my results.

[CA713937]

OK, 130MB/min is much better then 8MB/min!

[Harry Lubansky]

I will be testing out the VS80 tape drive Thursday when I go back on site. I will try the diagnostics then, and other suggestions from the group. I appreciate the time many of you have taken to help. I left the server up with the old tape drive to get the company back into production for the week, so backup has been normal for the week. I will update the response on Friday.

[David Richards_3]

Bumping the block size up to 64K is now giving me 177mb/min. Up from about 8mb/min.

Thanks Dave for your help. Veritas had no idea. They told me to get a new SCSI card, new cable, new office, etc.