scsi slowdown LTO2 drives

[emjaycee]

Using Solstice backup 6.1 with HP MSL6030 tape library with 2 LTO2 drives connected to a Dual Channel LVD controller on a Sun V240 with one drive on each channel of the controller. When a backup is started the second drive runs very slow and we get messages that scsi bus is syncing to slower speed such as "disabled wide SCSI mode" then, "reverting to async mode".
Restores are also very slow,a server has crashed but restoring will take about 3-4 days at this rate.
Any ideas on where to start looking for the answer to slow mode?

 

[605]

Everything seems to be alright up to the LVD controller. So it could be the cable or the drive or even the media.

 

[emjaycee]

Thanks for taking the time to answer 605, this happens on every tape so that rules media out. Will try replaceing cables when we get this restore finally done.

 

[appUT]

which scsi card are you using, and how many LTO-2 drives??
the 29160 adaptec scsi card runs at a max of 160MB per sec. Since the lto-2 tape runs at 45 to 50 MB per sec than you could be saturating the scsi bus with multiple tape drives or additional hard drives.

just a thought

 

[speculos]

We have similar problems with MSL6030, 2 LTO-3.
Everything is ok with Tape1, but scsi errors with Tape0 with differents media; changing Tape0 doesn't solve the problem.
In this cas HP recomends to change the SCSI adapter, cables and terminators.

 

[emjaycee]

Thanks for the input appUT & speculos,
The SCSI card is LVD ( 80MB ) but if I disable the first drive(the one that works) the second drive still produces errors and SCSI slowdown. We have a second library which I have tried, but both drives produce the same errors and scsi slowdown, even if one is disabled. The only drive that works is the first drive in the first library. The second library was connected using different cables as well.
I have checked the firmware and it is the same on all 4 drives and the same on both libraries.

 

[emjaycee]

For future reference
Finally got HP tech out ( needed to bring a win server with him to run Library and Tape Tools )
Turns out the short interconnect cables ( between drives or between drives and library controller ) were faulty.
Definately 2 on the second library and probably 1 on the first library. Must have had a run of bad cables in production.
Funny how after all the calls you make things don't happen until you get a tech person on the line.