[rescue] SCSI2SD formatting

[Sandwich Maker]

" From: CLIFFORD HAIGHT <klemish at hotmail.com>
" 
" I picked one of these up after buy some larger scsi drive and having them not
" last long....
" As I understand SunOS has limitation of 2GB per partition but the root
" partition must be 1 gb and first.

i think obp at some point grew the boot limit to 2G.

" So there by to get the biggest drive I cam up with something like
" 
" Cylinder: 1567, Head: 255, Track: 399585, Sector Size: 512, Sector/Track: 63
" bytes = 12889013760, kb = 12586927.5, MB=12586928,GB=12GB
" 
" so in theory a format.dat entry would looks something like this based on my
" understanding
" 
" disk_type="codesrc 12" \
"      : ctlr = SCSI : fmt_time = 4 \
"      : ncyl = 1565 : acyl = 2 : pcyl= 1567 \
"      : nhead = 255 : nsect = 25173855 : rpm = 7200 \
"      : bpt = 32256 : bps = 512 \
" 
" partition="codesrc 12" \
"      : c = 0, 10046256184125
" 
" Does this track...     I am a little confused on the partition.    I would
" assume that partions would need to be end to end, this is the case with linux.
" However many of the examples I have looked at overlap.

it's a convention that c is the whole disk and overlaps all, to make
backup and/or disk imaging easier.  partitions don't ordinarily overlap
otherwise.

nsect is supposed to be the number of sectors per track.

format.dat's partition table format is
[partition] = [starting cylinder], [sector count]
which is a hangover from very old days.

i don't know how large format's integers are for heads and sectors,
but stick to binary multiples and suppose:

nhead = 128 : nsect = 128 : ncyl = 1664 : acyl = 2 : pcyl = 1666

so:

a =	0,	2097152
b =	128,	4194304
c =	0,	27262976
d =	384,	4194304
e =	640,	4194304
f =	896,	4194304
g =	1152,	4194304
h =	1408,	4194304

and you could forego the customary usage of c and make it another
ordinary 2G partition, and then ncyl would be 1920.

acyl = 2 is also a long-ago convention from disks were quite tiny by
modern standards.  it's supposed to reserve enough sectors to back the
disk toc up.  i've set it to 1 on 4G disks.

i'd be tempted to try setting nhead, nsect, and rpm up and up until i
found format's limits, just out of curiosity.
________________________________________________________________________
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen
adh at an.bradford.ma.us                       and think what none thought