Problem trying to install SCSI disk drive on a 240/GTX.

[Brian Sturgill]

I am trying to install an HP 97540 SCSI disk drive on a 240/GTX.
99% of the time things work fine, however I sometimes get the following:

	sc0,5: Resetting SCSI bus: unexpected reselection
	dks0d5s6 bad return 2 from scsi driver

When this happens (it has happened twice in the 3 days we have been running
the drive), then strange things happen with the disk.. for example fsck says it
cannot find blocks.  Powerdown then back up and fsck can read them again.

I have several questions:

1) Has anyone else put an HP SCSI-2 drive on an SGI system?

2) What does the error message mean?  What could cause it?

3) We had thought we were ordering a SCSI-1 drive, can the 240's scsi controller
	use a SCSI-2 drive?

4) The drive has an option that enables/disables the "Unit Attention" function.
	Anybody know whether this should be disabled/enabled?  What
	does it do?  (I have tried it both ways, I get the errors above
	regardless of the whether or not the "UA" jumper is in.)
	Why would one want this to be an option?

5) Anybody know of a good book on SCSI?  In particular it is
	very unclear to me what the differences between SCSI-1 and SCSI-2
	are.

Brian
-------------
Brian Sturgill
brian at cs.utah.edu