HP DLT80 performance problems on HP-UX 10.20

[Jim Haeseker]

Is anyone successfully using HP DLT80 / DLT8000 tape drives on an HP-UX 10.20 system?

I recently installed one on each of my two HP-UX systems (K580 and D330) to replace a problem AIT solution. Both systems run HP-UX 10.20 and have relatively recent patch levels. Each system recognized their respective tape drive, associated it to the stape kernel driver, and seems to work fine with fbackup. Still, I sporadically see performance problems, such as a normal 2 hour backup on the K580 jumping to 4 hours for no apparent reason. The D330 exhibits similar problems flipping between 3 and 7 hour backups.

I've been working with the HPRC on this for two weeks now without resolution. My initial assumption was that I had a compression problem, but several performance tests confirmed compression is working. I've run several more tests and altered various parameters (at HPRC's request) that haven't helped. I'm now being asked to remove one filesystem at a time from my fbackup graph file in an attempt to isolate whether a particular filesystem MIGHT be taking an inordinate amount of time to back up. I'm not very optimistic and I think HPRC is running out of options.

I fear the "HP-UX 10.20 isn't supported" card will be played soon. Unfortunately, I'm not in a position to upgrade these boxes as the applications running on them are sensitive to the OS version (and upgrading the apps isn't scheduled anytime soon).

I would appreciate a response from anyone who's had experience (good or bad) with HP DLT8000 tape drives running on any HP-UX 10.20 system along with any suggestions you might have for a resolution. Thanks.

[Shaikh Imran]

Hi,
DLT 80 will also work with 9.x O.S.
Please refer the following Link for more details:
http://www.hp.com/products1/storage/products/tapebackup/dlt_tapedrives/dlt8000_drives/faqs.html

Regards,

[Vincent Farrugia]

Hello,

On K and D-Class servers, you definately NEED a SCSI card on the HSC bus, not on the HP-PB bus. HSC runs at 12-15Mb/s, which can stream DLT8000 well (being 12Mb/s compressed). HP-PB can only stream 7-10Mb/s, which at times is not enough for DLT8000. See the below thread for details.

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=4564

If your DLT8000 is connected to a 28655A or 28696A card (HP-PB), remove it. You need a A2969A card (HSC SCSI card) in order for your DLT8000 to work well.

HTH,
Vince

[Jim Haeseker]

Shaikh:
Thanks for confirming support under 10.20

Vincent:
My K580 is using a dedicated A2969A FWD SCSI card for the DLT8000. The D330 box has a different slot structure and I'm not certain of the card's part#, but it is dedicated to the DLT8000.

An ioscan shows the cards used on both systems as "GSC add-on Fast/Wide SCSI" using driver "c720". Backups are consistently successful - they just aren't consistent in duration.

The K580's DLT8000 backs up about 50Gb (before compression) and has been more stable than the D330. Since installation on the K580, we had 30 'good' backups (at 2 hrs ea.), 7 'bad' backups (at 4 hrs ea.), a system reboot, then 7 more 'good' backups as of today. No telling why (or if) the reboot had anything to do w/ the duration change.

The D330's DLT8000 backs up about 80Gb (before compression). Since installation, the D330 had 3 'bad' backups (at 7 hrs ea.), 4 'good' backups (at 3 hrs ea.), 3 'bad', 1 'good', and 7 'bad' as of today. Reboots of this system had no impact on backup duration.

As we all know, if it was an easy problem - it would already be solved. I appreciate any suggestions on what to look at next.

Is anyone out there successfully running DLT8000s on an HP-UX 10.20 system? (Nothing better than first-hand experience.)