No disklabel, but it still boots

[Pete Yandell]

I have a disk which apparently has no disklabel, but still boots and 
mounts several partitions, and I'm puzzled as to how this can be. Where 
is it pulling the partition information from if not the disklabel?

$ df
Filesystem  1K-blocks    Used     Avail Capacity  Mounted on
/dev/ad6s1a    128990   48054     70618    40%    /
/dev/ad6s1f    257998      18    237342     0%    /tmp
/dev/ad6s1g 151150778 2131440 136927276     2%    /usr
/dev/ad6s1e    257998    7546    229814     3%    /var
procfs              4       4         0   100%    /proc

$ disklabel ad6
# /dev/ad6:
type: unknown
disk: amnesiac
label: fictitious
flags:
bytes/sector: 512
sectors/track: 63
tracks/cylinder: 255
sectors/cylinder: 16065
cylinders: 19457
sectors/unit: 312581808
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # milliseconds
track-to-track seek: 0  # milliseconds
drivedata: 0

8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
   c: 312581808        0    unused        0     0        # (Cyl.    0 - 
19457*)

$ disklabel -r ad6                                                  ~
disklabel: bad pack magic number (label is damaged, or pack is 
unlabeled)


If I boot off the fixit CD, I can't see or mount any FreeBSD partitions 
on the disk.

This is on a HP Proliant DL360 Gen 4 with a single Maxtor 160GB SATA 
drive running FreeBSD 4.10.

Thanks,

Pete Yandell