[rescue] SCSI2SD formatting

Mouse mouse at Rodents-Montreal.ORG
Fri Feb 19 19:28:41 CST 2016

> As I understand SunOS has limitation of 2GB per partition but the
> root partition must be 1 gb and first.

Not quite.  The _boot_ partition (which is usually, but not
necessarily, root) must be entirely below the 1G point.  It does not
have to be 1G (it may be less) and I _think_ it does not need to be
first.  (It might need to be partition a, which is not necessarily the
first partition, though some partitioning tools will insist it is.)

Also, this is ROM-rev-dependent, and, I think, hardware-dependent as
well in some cases.  (The issue is that the ROM code uses only 6-byte
CDBs for its disk accesses, which include only 21 bits of sector
number.  Since SunOS of this vintage requires 512-byte sectors, this
imposes a 1G limit.)

Strictly speaking, the boot partition does not have to be entirely
below the 1G mark; rather, all the blocks read during the boot process
must be.  However, unless you are a filesystem wizard (in which case
you probably would not be asking this :-), the only practical way to
ensure this is to put the entire partition below the 1G point.

> So there by to get the biggest drive I cam up with something like
> [...]
> so in theory a format.dat entry would looks something like this based
> on my understanding
> [...]

It's been too long; I don't recall enough of format.dat to say anything
useful here.  But...

> partition="codesrc 12" \
>      : c = 0, 10046256184125

...this looks dubious.  If that second number is bytes, it's over 9 TB,
and you indicated the disk was only about 12 GB; if it's blocks or
kilobytes or some such, it's even larger.  So it probably is wrong.

> 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.

They do not need to be (and indeed the c partition normally is the
whole disk, overlapping all other partitions).  You can overlap them
arbitrarily, given a partitioning tool willing to generate such a
partition table.  However, in most cases, doing this is a mistake,
because it is an invitation to create overlapping filesystems, which
will explode badly.  (Again, exceptions are possible, but if you're
enough of a filesystem wizard to make that work, you don't need any of
this explained to you.)

It actually would surprise me if the same weren't true of Linux, but I
know it less well, so for all I know it's possible that its kernel
gratuitously refuses to use a partition table with unexpected overlap.

>   a
>   0,837188015343.75

>   b
>   837188015344.75,1674376030688.5

I don't understand these numbers.  They are well over 12G - and they're
fractional, too.  Where did you get them?

> I tried setting the disk label to SUN2.1 but for whatever reason I
> seem to be running out of room way to quick using the default
> partitioning scheme

Given the numbers you're quoting here, I would expect you to be running
out of room, many times over, with just the first partition.  So I
suspect there is something I'm missing.

/~\ The ASCII				  Mouse
\ / Ribbon Campaign
 X  Against HTML		mouse at rodents-montreal.org
/ \ Email!	     7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B

More information about the rescue mailing list