Formatting SCSI drives for Ultrix

[Dirk Grunwald]

This stems from some notes in comp.sys.sun.

I have a pmax & a CDC Wren V 702Mb drive. I formatted the drive using
Sun format to enable the cache enable. Using their figures for
cylinders and the like, I get about 580Mb out of this drive.

Now, someone tells me that I should just ignore the alternate
cylinders and spare sectors -- the SCSI drive handles all that for me.
I should simply take the total number of sectors, divide by the S/T
and the T/C to get the total number of cylinders.

Doing this would recover mucho space (like, 30Mb or so, I figure).
This person said that ``Sunos 4.0 and above'' interact with the SCSI
error-correct/sector-patching commands to map ``hidden'' sectors when
I have hard failures & need to flaw sectors. The entries in Suns
version of format.dat are allegedly holdovers from SMD based systems
and there is no need for alternate cylinders, except possibly to write
the labels.

Do people in the know w.r.t. SCSI disks on DEC machines believe this
is the case? Will Ultrix use the SCSI spares, or does it need its own
spares?

What geometry are people using for WREN V drives? What hasn't worked?

30mb is a big hunk of cheese to throw away, particularly on a rather
crowded disk like this.