CDC Wren IV, 4.0.3 and format

[Douglas N. Arnold]

William D. Shoaff writes
>>  We have experienced problems trying to format a CDC Wren IV
>>  94171-344 under 4.0.3 on a Sun 3/50.  We went with the info in the
>>  format.dat file, not changing anything.  When we ran format, it said
>>  the disk was formatted, but no defect list was found, using original
>>  we committed the manufacturer's list, and decided to label the drive
>>  (it was supposely formatted).  Label failed with write errors on cyl
>>  1546.  We then decided we had better format it, but it hung on the
>>  verify pass.

I had a similar experience trying to format a CDC Wren IV 94171 on a
SPARCStation 1 running 4.0.3.  The format.dat entry provided didn't work.
I did a lot of reading of back issues of Sun-Spots, and a fair amount of
trial and error and came up with

  1356 cylinders, 2 alternate cylinders, 1362 physical cylinders,
  9 heads, 48 sectors per track

That comes to 585,792 sectors, or 299,925,504 bytes.  Since the OEM manual
that came with the disk says that "Model 94171 has a factory formatted
storage capacity of 298 megabytes", I figured I didn't do too bad.

I don't feel comfortable with the way I arrived at these numbers, but I
have been using the disk for about 2 weeks and everything seems to work.
A general question to people out there who know: ISN'T THERE A BETTER WAY?
I've gone through this twice, once with a Wren IV and once with a Wren V,
and both times I've arrived at the formatting data basically by guess
work.  From reading Sun-Spots, I see that I'm not alone.

By the way, I partitioned the disk into a root partition of 45 cylinders,
a /usr partition of 1167 cylinders, and a swap partition of 144 cylinders.
This works out to 32 MB of swap, and after making the filesystems, 9 MB +
236 MB in the two partitions.

	  dna at fredholm.psu.edu
	    Douglas N. Arnold
	    Department of Mathematics
	    The Pennsylvania State University
	    University Park, PA   16802