sunlabel only allocating half the disk?

[John Nielsen]

On Wednesday 14 December 2005 12:08 pm, John Nielsen wrote:
> I am running FreeBSD 6.0-BETA5 on a Sun Ultra 5 station.  The box has two
> IDE hard drives, one 9GB and one 60GB.  The entire OS is installed on the
> 9GB drive, with the 60GB being for aux. storage.  When I installed the
> system (perhaps using an earlier 6.0 beta), sunlabel did its thing on both
> drives and I had the amount of space I expected.
>
> I recently pulled the 60GB drive out of the system for use on another
> project (in an i386 box).  Now the drive is reinstalled in the Sun box and
> shows up as ad1 as expected in the kernel boot messages:
>
> ad0: 8693MB <Seagate ST39111A 3.21> at ata2-master WDMA2
> ad1: 57259MB <MAXTOR 6L060J3 A93.0500> at ata2-slave WDMA2
> acd0: CDRW <CRD-8322B/1.03> at ata3-master PIO4
>
> I zeroed the drive (dd if=/dev/zero of=/dev/ad1 bs=1m) and re-labeled it:
>
> sunlabel -w ad1 auto
>
> That appeared to work, but on closer inspection the raw partition is less
> than half the size of the drive:
>
> # sunlabel ad1
> # /dev/ad1:
> text: FreeBSD56G cyl 50798 alt 2 hd 16 sec 63
> bytes/sector: 512
> sectors/cylinder: 1008
> sectors/unit: 51204384
>
> 8 partitions:
> #
> #    size       offset
> #    ---------- ----------
>   c:   51204384          0
>
> And with the -h flag:
>   c:      26.2G         0B

After some trial and error and manual calculations, I came up with this label, 
which seems to work fine:

# /dev/ad1:
text: FreeBSD56G cyl 58166 alt 2 hd 32 sec 63
bytes/sector: 512
sectors/cylinder: 2016
sectors/unit: 117262656

8 partitions:
#
# Size is in sectors.
# Offset is in cylinders.
#    size       offset
#    ---------- ----------
  c:  117262656          0
  d:  117262656          0

I'm still curious as to why the automatically generated label was so far 
wrong, and why it worked properly the first time I did the same command with 
the same disk.

JN