NEC D-2363 disk geometry for Rimfire 3200 controller

[Paul Martin]

Can anyone out there in net land give some advice in calculating the
geometry of a NEC D-2363 900MB disk running on the following combination
of hardware and software : 

	Rimfire 3200 controller,
	Sun 3/280S, OS 4.0.1

Our problem is that the NEC D-2363 disk is supposed to deliver a disk
capacity of approx 900MB. We have a similar disk using a Sun Xylogics 7053
SMD controller on a second Sun server and this indeed does provide us with
the correct disk capacity. The capacity difference stems from the fact
that the recommended geometry of the *SAME* disk is substantially
different for the two controllers, particularly in the number of heads.

For the Xylogics controller, /etc/format.dat uses 27 heads, 964 cylinders
and 67 sec/cyl giving a total disk capacity of 1743876 sectors or 851 MB
of real data space.

For the Rimfire rfutil suggests the use of 19 heads, 1022 cylinders and 67
sec/cyl giving a total disk capacity of 1301006 sectors or *ONLY* 635MB.

I tried changing the geometry of the disk as seen by the Rimfire
controller to make it match that of the Xylogics controller. I was able to
format, label and newfs all the disk partitions without any problems. The
UNIX commands newfs, df, mount, umount and dkinfo all worked - everything
except for fsck which complained about a corrupt super block and
instructed the use of the "-b" option to use an alternate super block.
This made no difference every superblock seemed to be corrupted in the
same way. However I was still able to mount/umount all the disk partitions
?? Perhaps some guru can explain that one ?

Well I have now reverted back to the rfutil recommended geometry as this
is the only labelling that I could find that would allow fsck to work. I
really did not want to leave a system that would always hang on reboot -
even if it meant losing more than 200 MB of disk space.

Obviously there is something wrong with the geometry given in rfutil - and
I would rather not experiment on our network master machine. Can anyone
else throw some light on my confusion.

Thanks in advance for any assistance,

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Paul Martin  			
European Computer-Industry Research Centre        ECRC, Arabellastr. 17/II 
US:     paul%ecrcvax.uucp at pyramid.pyramid.com     8000 Muenchen 81, West Germany
        ..!pyramid!ecrcvax!paul		          Tel. (089) 92699 124
Europe: paul at ecrcvax.uucp
	..!unido!ecrcvax!paul
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