Format.dat for CDC9720-1230?

[Steve Senum]

In article <9987 at brazos.Rice.edu> poffen at sj.ate.slb.com (Russ Poffenberger) writes:
>
>In article <9892 at brazos.Rice.edu> xait!mgb at cs.utexas.edu (Michael G. Burner) writes:
>>
>>disk_type = "CDC 9720-1230" \
>>        : ctlr = XD7053 \
>>        : ncyl = 1633 : acyl = 2 : pcyl = 1635 : nhead = 15 : nsect = 83 \
>>        : rpm = 3600 : bpt = 50400 : bps = 600
>
>This will not work correctly. The 7053 requires an extra sector configured
>on the drive for slip sectoring. This implies that the drive would have to
>be set for 84 sectors. At 84 sectors, a 9720-1230 has exactly 600 bytes
>per sector.  Since the 7053 uses 512 byte sectors with a minimum of 88
>bytes overhead, plus 4 bytes minimum for the runt sector, this adds up to
>at least 604 bytes per sector required. This means that the next setting
>of 83 sectors on the drive (606 bytes per sector) and 82 set in the
>format.dat parameters is the correct setting.

When I first installed our CDC Sabre 1230 drive I called Xylogics support
at 617-272-8140.  They said that my 7053 controller had to be at a certain
ECO level (a "106" in the part number on the board instead of a "105") in
order to handle the 1230's 3.0 Megabyte/second transfer rate.  They also
said to use a sector size of 599 (instead of the normal 600).  Most (if
not all) of the 7053 controllers sold by Sun are *not* at the proper ECO
level.  The ones sold through distributors are.

My format.dat entries are:

disk_type = "CDC 9720-1230" \
	: ctlr = XD7053 \
	: ncyl = 1633 : acyl = 2 : pcyl = 1635 : nhead = 15 : nsect = 83 \
	: rpm = 3600 : bpt = 50400 : bps = 599

partition = "CDC 9720-1230" \
	: disk = "CDC 9720-1230" : ctlr = XD7053 \
	: a = 0, 33615 : b = 27, 67230: c = 0, 2033085: g = 81, 1932240

The partition entry is somewhat arbitrary.

Steve Senum (sjs at network.com)