Re: What?! ANOTHER HD question???

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <15326FYCLRODYHWMQXQ@ods.sol.net>,  <dreamer@ods.sol.net> wrote:
> 
> My friend has a CMS drive (Seagate mech) and a Western Digital
> Preference drive that he was running on a ROM 1 with the SCSI Rev. C
> card.  Unbeknownst to him, BOTH drives were terminated (the CMS
> internally with the resistors and the WD externally with it's own
> special type of SCSI ID/Termination selector), and he ran it for a year
> or so that way before it pooped out on him.
> 
> Question 1:  Does terminating both external drives damage data, the
> mech, or both?

It certainly won't cause any damage to the hardware.  Having too much
termination (or not supplying termination power) can cause data
corruption, which will usually be exhibited as an I/O error of some
kind or failure to boot.

Note that the original Apple SCSI card is not terminated.  If you have
two drives connected to it, you are supposed to have both drives
terminated (either internally or externally).

With an Apple High-Speed SCSI card or a RamFast, the SCSI card is
terminated, so only the drive at the far end of the chain should be
terminated.

> To summarize:  With just the CMS I would get the "Check startup device"
> when I attempted to boot from it.  With the WD and then the CMS (in a
> chain) it would hang with no message when I booted from it.  When
> booting from the 3.5 it would hang until I powered down both HDs.  I was
> only able to access the WD after disconnected the CMS.  No programs got
> me past this problem.  I ran an extensive diagnostic program that tested
> various aspects of the //gs and it came through clean.
> 
> Question 2:  What to do?  Did the double termination permanently fry the
> CMS, or is there some way I can reinitialize it for use on the GS again?

It sounds like the CMS has developed a fault, but I doubt it has
anything to do with termination.  It could just be data corruption on
the drive (e.g. a checksum error in a critical portion of the disk)
that is preventing the drive from completing its initialization
sequence, and the computer is not timing out.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand