Ultrix Disk Partitioning Problem

[Dan Ts'o]

>>Actually, I don't understand why it has to look like an RA81.  For
>one thing, RA81's have no hp-type interface: they are MSCP drives.
>
>The size of an RA81 is:
>	:ty=winchester:ns#51:nt#14:nc#1248:pc#891072:
>
>The size of an Eagle is:
>	:ty=winchester:ns#48:nt#20:nc#842:rm#3961:pc#808320:
>
>Interestingly, in our ISI m68k disktab, I also find:
>beagle|Snoopy| Brain-Damaged Eagle (47 sectors courtesy of SC03):\
>	:ty=winchester:ns#47:nt#20:nc#842:rm#3961:pc#791480:

	I believe, Joe, you're thinking of an SC03, not an SC03/MS, which
IS an MSCP controller. Thus the hp driver is irrelevant. I believe your
partitions are fine for an SC03, which is like a Qbus SC750, SC7000, etc.

	However, the SC03/MS looks like a UDA-50. An Eagle on the SC03/MS
is 722770 sectors long. MSCP disk software doesn't care about sectors/track
tracks/cylinder. It is a bit crazy that the SC03/MS loses so much of the
Eagle, > 10%. I can understand using some for bad sector replacement, but...

	Until recently, the SC03/MS wouldn't even boot under Ultrix-32m.
That meant/means it might be reasonable to actually use a SC03 and get more
of the Eagle (the SC03 won't boot either since the MVAX II doesn't have
the boot ROMS for an HP disk, although you could write one, and ...). If
you're thinking of going that route, I would suggest looking into another
Qbus - HP-type controller, from Spectralogics. They will get much higher
performance from the Eagle since they can do 1:1 sector interleaving 
(I think the SC03 is 3:1) and they have block-mode DMA's, which the SC03
doesn't. 

					Cheers,
					Dan Ts'o
					Dept. Neurobiology
					Rockefeller Univ.
					1230 York Ave.
					NY, NY 10021
					212-570-7671
					...cmcl2!rna!dan
					rna!dan at cmcl2.arpa