[rescue] SCSI2SD formatting
adh at an.bradford.ma.us
Fri Feb 19 15:41:03 CST 2016
" 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
" 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
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
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
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