Slow performance on SureStore 818

[CA966047]

I have an 818 autoloader, a 1/9 autoloader, and also a DLT8000 stand-alone tape drive.
I???m running BackupExec 8.6 on a Win2k SP3 server.
My SureStore 818 is consistently running b/u jobs around 30mb/min or less.
My SureStore 1/9 autoloader always runs b/u jobs around 300 ??? 400 mb/min. and the DLT8000 stand-alone drive always runs around 250 ??? 300 mb/min.
I???m running all this on a Compaq ML530 server with 3 different SCSI cards (nothing is daisy-chained).
The 1/9 and the 818 each run off their own Compaq 64bit/66mhz Wide Ultra SCSI 3 card and the Stand-alone drive runs on an Adaptec 2940 card.
I???ve tried changing all the external hardware on the 818, switching the SCSI cards, cable and terminator w/ no improvement.
Each autoloader runs a cleaning tape once/week.
The kicker is that if I take a job that runs 30mb/min on the 818 and then run it on my 1/9 autoloader with no other changes, it runs at 350 mb/min!
I???ve updated to the latest firmware on both autoloaders and the DLT8000 stand-alone.
I???ve called HP support on this 3 different times and each time they concluded it was a bad drive so they sent me out a replacement autoloader. The replacement runs up to about 120 mb/min for a week or so, then gradually degrades back to 30mb/min.
Anyone have any suggestions?

[Eugeny Brychkov]

1. Do not overclean DLT drives. Clean them only by their request;
2. if you'll look at autoloder from the back there're 2 devices daisy-chained - robot and drive. Make sure there's appropriate terminator installed. Try disconnecting robot off the SCSI bus and with drive only connected to the SCSI controller
Eugeny

[Curtis Ballard]

Eugeny has a good suggestion, move the library controller so it is on a different bus than the drive (or just take it off the bus and test the drive as a standalone), and see if that makes any difference.

There have been some problems with Adaptec drivers (and the Compaq/HP version of it) where the driver will negotiate for the wrong transfer rate with the drive when a library controller is on the same bus. The HP driver version 6.1.550.100 works most of the time. There should be a new version coming shortly that so far seems to always work.

If you have the Compaq "Insight Manager" installed run the web browser and check the negotiated transfer rate for the DLT8000 drive in the 818. You typically get to that at https://localhost:2381/ then under "Storage" select the SCSI controller you want and then in the left pane select the tape drive you want. Under "SCSI Bus Information" it should report the "Current Width" and "Current Speed" values for the drive.

[meloni]

I had a similar case where after two month of activity the thoughput falled down to 30 Mb/s, the cause was overcleaning, in fact they cleaned the drive once per week plus each time it was reported by the drive, and as they have some defective cartridge too, they thought that cleaning was the solution,but it wasn't.
So check for bad cartridges and do not overclean as Eugeny already said