Hey thanks.

I had some trouble with the Sparc's need for partitions being whole
multiples of cylinders, but it works now.

I then built a ccd with the thing.  Interesting to note that the
disktab entry for the ccd creates a label where

ns: 2048
nt: 1

resulting in the same net effect you suggested with

ns: 64
nt: 32

Any pros or cons to either approach or is this all just arbitrary
fiction?

--
Eric W. Bates

 > From: der Mouse  <mouse@Rodents.Montreal.QC.CA>
 > Date: Fri, 28 Nov 1997 07:35:47 -0500 (EST)
 >
 > > I have a Quantum Fireball_TM2110S (2.1 Gb).
 >
 > (Probably closer to 2G; disk manufacturers routinely lie about their
 > disks' sizes - see below.)
 >
 > > I do not believe there is a description of this device in the
 > > disktab.
 >
 > > Has anyone written one?  Or point me towards more info to read about
 > > how to write one?
 >
 > > So far I have: [...]
 >
 > During boot, the kernel prints lines describing the device, stuff like
 >
 > sd0 at scsibus0 targ 0 lun 0: <IBM, WDS-L160, S510> SCSI1 0/direct fixed
 > sd0: 163MB, 1923 cyl, 4 head, 43 sec, 512 bytes/sec x 334601 sectors
 >
 > The only number I pay any attention to here is the "sectors" count
 > (though the size in MB is printed, and you will likely find your
 > "2.1GB" disk is actually more like 2G, if that - I have a Seagate
 > ST12400N that was sold as 2.1G, but it's actually 4194685 sectors,
 > which is only marginally more than 2G (2.00018+, actually); NetBSD
 > prints "2048MB" for it).
 >
 > The rest of the disklabel I fill in with numbers like these:
 >
 > sunlabel> L
 > ascii: Fujitsu M2266S-512, 1658cx15hx84s, 2107704x512
 > rpm: 3600       pcyl: 1032      apc: 0          obs1: 0
 > obs2: 0         intrlv: 1       ncyl: 1030      acyl: 0
 > nhead: 32       nsect: 64       obs3: 0         obs4: 0
 > sunlabel>
 >
 > (where the ascii label string contains manufacturer, model, the numbers
 > reported by the kernel at boot time, and the actual size).  That is, I
 > completely ignore the sect/track and tracks/cyl values, using 64 and 32
 > for those (thus using "cylinders" of 1MB).  I then set the cylinders
 > value to the size of the disk in megabytes, rounded up.
 >
 > I do this because almost all disks these days - especially even vaguely
 > modern disks - are ZBR disks, on which the number of sectors per track
 > varies depending on the cylinder number.  It thus is simply not
 > possible to "tell the truth" in the disk label.  Since disks also tend
 > to have large caches and other factors which wreck the neat model FFS's
 > knowledge of disk geometry was built around, I don't bother even
 > trying, and instead go for the convenience of having 1MB "cylinders" on
 > all my disks.
 >
 > In terms of disklabel, this becomes something like
 >
 > > #/dev/rsd4c
 > > type: SCSI
 > > disk: SCSI disk
 > > label: Quantum TM2110S
 > > flags:
 > > bytes/sector: 512
 > sectors/track: 64
 > tracks/cylinder: 32
 > sectors/cylinder: 2048
 > cylinders: (total sectors, divided by 2048, rounded up)
 > total sectors: (per the boot-time message)
 > > rpm: 4500
 > > interleave: 1
 > > trackskew: 0
 > > cylinderskew: 0
 > > headswitch: 0		# milliseconds
 > > track-to-track seek: 0	# milliseconds
 > > drivedata: 0
 >
 > 					der Mouse
 >
 > 			       mouse@rodents.montreal.qc.ca
 > 		     7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B