Ultrium 448 External - Horrible Performance

[Tim Perdue]

I received my new external Ultrium 448 tape drive and it has absolutely awful performance so far. It's hooked to an adaptec 29160 SCSI card and is the only device on the card.

A 62GB backup took 16 hours to run - less than 4GB/hr. The advertised rating is 89GB/hour backup performance.

The LTT test tools don't tell anything except that it runs at 2MB/sec, and gives no information on where to look for a solution.

Any Ideas?

[Richard Bickers · Accepted solution]

It should work fine so the issue must be with cabling, termination, connectors, ... Do you have another cable to try? Do check the auto-termination is enabled for the external drive.

You can also look at the LTT support ticket which will tell you if it sees anything wrong with the SCSI configuration. Look in the drive health -> device analysis section. This will warn you about low negotiated burst rates and any bus parity errors the drive may have received. Also the drive configuration -> interface will tell you what SCSI burst rates it's set up for.

When the HBA discovers the drive they both negotiate the fastest data rate they can both manage. If there's an issue with the cabling/termination etc then you end up with very low data rates. During operation, the HBA can re-negotiate slower if it sees parity errors so these rates can get very slow over time too. They never go up! Only solution is to power cycle the HBA and start again. Worth a try.

Good luck. It's bound to be cabling. The drives are fine and tested at full speed in production.

[Tim Perdue]

Thank you for your support. I did resolve the problem.

I replaced the SCSI Card with an LSI Logic Ultra 320 and replaced the cable with 18" SCSI cable and now I receive 41MB/Sec performance on the DevPerf test, which is awesome.

I don't know if the problem was with the cable or the Adaptec card, but this issue is resolved.

Thanks again,

Tim Perdue