If you are having backup speed issues read this ! ! ! ! 1

[tech187]

I have several Dell servers with Dell Powervault 122t LTO Tape Libraries. After loading Arcserve 2000 and running some backup tests my backup speed was barely over 100mb per minute. I then loaded the latest Adaptec scsi driver(version 6.0.4000.105) and my backup speed jumped to 1.8gb per minute. Here is the reason the previous drivers were so slow.
(6.0.4000.0100)

- With non-disk device such as HP Ultrium Tape drive..., the
driver did not negotiate transfer rate, all subsequent I/O
transfers occurred as asynchronous speeds.

Hope this helps ! ! ! !

 

[Ourcup]

The root cause of the problem is, that both the Array Controller and the SCSII board where the Tape device is attached to, switch back to narrow SCSII mode when there is high load on the bus. This especially happens whilst taking backups. We have the same issue with the backups not being able to finish within 1 day. Data rate is always around 120 MB/minute.
We are applying the following patches to solve the problem:
1. ProLiant Support Pack for Microsoft Windows 2000 v6-20
2. Adaptec SCSI board adpu160m v2 (Driver Version: 6.1.550.100)
The patch has to be applied to all servers. There is a reboot needed after applying this patch.
After doing this we are achieving much higher data rates (850MB/min locally and 550MB/min for the remote server) and where able to run the complete backup within 2 hours.

Details regarding the problem can be found at:

http://wwss1pro.compaq.com/support/...=808&source=EM020409_CW02.xml&dt=3&docid=9166