Variable throughput on LTO3 drive

[MarkDym]

Hi

I recently installed an external Quantum LTO3 drive. The drive appears to be working fine, but in the time we have had it (less than 2 weeks), throughput has varied.

Normal backup operations take 6.5 hrs to backup 315GB of data. Twice this has dropped to 13hrs. Checking the logs, the average throughput for the drive is 800MB per minute. However, throughput averages 400MB per minute when it takes 13hrs to complete the backup.

I have no idea why this happening. Anyone else experienced this or know how I can ensure that the throughput remains consistent please?

Thanks

Mark

 

[davidmichel]

If you have multiple targets then try out mulitiplex. HP has a tech doc that specifies with LTO3 it is necessary to use multiplex to get the full throughput of the drive.

Check out the job log to see the throughput for every session. Then see if specific targets are consistently fast or slow.
For the slow ones check to see if the # of directories and files is a lot more.
Many small files will be slower.
Compressed data (zip, mp3, jpg, etc) will be slower.
Check for a virus detection program scanning all outgoing files.
Defrag the drive, this can have a tremendous effect.

 

[MarkDym]

Hi David, thanks for the response

I contacted the tape drive manufacturer, Quantum, and it was sorted out pretty quick. I had been using SCSI ID 8 for the drive, and was advised to use ID 6 instead. Since then the drive throughput has been consistently over 800MB per sec.