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Slow speed on Ultrium drive

Mike Kobylarz
Occasional Visitor

Slow speed on Ultrium drive

Running an Ultrium drive with an Adaptec 29160 controller through Windows 2000 Advanced Server SP2, Backup Exec 8.6.

When I first ran the backups, it was running about 300MB per minute, suddenly they've dropped to about 70MB per minute. They're faster local (about 100MB) but still about a 75 percent speed drop.

Any ideas on what I could check that would suddenly cause this to slow down like this. The server is a Dell PE 4600 with dual Xeon Processors, dual RAID controllers, one for internal RAID, one for an external array, plus the 29160. The CPU and memory utiliation never top 20-30 percent.

Thanks for any help.
Vincent Farrugia
Honored Contributor

Re: Slow speed on Ultrium drive


First of all, even 300Mb per minute is slow for an Ultrium. What Ultrium do you have; 215 or 230? 215 goes to speeds up to 7.5Mb per sec native, 15Mb per sec compressed, which would be between 450 and 900 Mb per minute. 230 is 15Mb per sec native speed, 30Mb per second compressed. I know these are theoretical, but 300Mb per minute can be seen on a DLT8000 drive as well if all things are right. I assume (and hope) you have the 215 model, which wouldn't be too bad.

As regards your problem, refer to the following document:

The second one seems very much in accordance to your problem, but all of them are relevant. Unfortunately, performance problems can be due to many things and can be due to only one thing... so good luck! :-)

Tape Drives RULE!!!
Michael Lampi
Trusted Contributor

Re: Slow speed on Ultrium drive

My guess is that the server is providing data to the tape drive below the minimum threshold that the Ultrium drive can stream. The result is that the tape must be repositioned to handle the data underrun.

I would suggest you try defragging the RAIDs and seeing if the speed of your backups improves.
A journey of 1000 steps ends in a mile.
Arimo Laine_2
Valued Contributor

Re: Slow speed on Ultrium drive

Another suggestion... disable Domain Validation from the SCSI BIOS.

Occasional Visitor

Re: Slow speed on Ultrium drive

how I do this and why is necesary disable domain validation in scsi bios?

thanks for all
Dave Dewar
Trusted Contributor

Re: Slow speed on Ultrium drive


Below is a link to a HP perf troubleshooting guide that makes use of the performance tools we have provided. See the second link for the ools.

This should help you pinpoint the problem

Performance issues are very rarely due to problems with the tape drive.

300MB per minute is pretty low for an Ultrium drive anyway and if things have got worse over a period of time this could point to disk fragmentation. The fact that you see a large drop on local backups support this.
You also suggest you are backing up over a network for some of the time. Remember that a 100baseT link will max out at 10MB/s and so if you have a Ultrium 230 that has a top native speed of 15MB/s you will not be utilising that to its full potential. Both the 215 and 230 will stream down to 6MB/s.

You might want to consider pulling all of you networked data over to the backup server raid system first and then just performing a local backup from raid to the tape drive.


Dave Dewar.