partition covering the whole slice

[Andriy Gapon]

I have a disk with two slices and each slices has a single real
partition covering the whole slice, sector-to-sector.
I don't remember how I managed to configure the disk this way, is this
even possible? :-)

$ gpart show
=>       63  781422705  ad12  MBR  (373G)
         63  209712447     1  freebsd  [active]  (100G)
  209712510  571705155     2  freebsd  [active]  (273G)
  781417665       5103        - free -  (2.5M)

=>        0  209712447  ufs/extbackup  BSD  (100G)
          0  209712447              1  freebsd-ufs  (100G)

=>        0  209712447  ad12s1  BSD  (100G)
          0  209712447       1  freebsd-ufs  (100G)

=>        0  571705155  ufs/extstuff  BSD  (273G)
          0  571705155             1  freebsd-ufs  (273G)

=>        0  571705155  ad12s2  BSD  (273G)
          0  571705155       1  freebsd-ufs  (273G)

You can immediately spot another oddity - I never used glabel on this
disk, but I did use tunefs -L to label the UFS filesystems within the
partitions.
Now it seems that the label of filesystems is also somehow recognized as
a label for the whole slice. E.g. "ufs/extbackup" is exatcly the same as
"ad12s1". Weird.

Here's some additional data:
$ ls -1  /dev/ad12*
/dev/ad12
/dev/ad12s1
/dev/ad12s1a
/dev/ad12s2
/dev/ad12s2a

Looks usual.

$ ls -1 /dev/ufs/
extbackup
extbackupa
extstuff
extstuffa

So there is one "normal" label for each filesystem and the second label
for it as a filesystem in partition "a" of a labeled slice.

There is nothing in /dev/label though.

And a bit more:
$ file -s /dev/ad12s1
/dev/ad12s1: Unix Fast File system [v2] (little-endian) last mounted on
/automnt/ufs/extbackupa, volume name extbackup, last written at Tue Dec
 2 17:47:21 2008, clean flag 1, readonly flag 0, number of blocks
13107027, number of data blocks 13002290, number of cylinder groups 35,
block size 65536, fragment size 8192, average file size 16384, average
number of files in dir 64, pending blocks to free 0, pending inodes to
free 0, system-wide uuid 0, minimum percentage of free blocks 8, TIME
optimization

$ file -s /dev/ad12s1a
/dev/ad12s1a: Unix Fast File system [v2] (little-endian) last mounted on
/automnt/ufs/extbackupa, volume name extbackup, last written at Tue Dec
 2 17:47:21 2008, clean flag 1, readonly flag 0, number of blocks
13107027, number of data blocks 13002290, number of cylinder groups 35,
block size 65536, fragment size 8192, average file size 16384, average
number of files in dir 64, pending blocks to free 0, pending inodes to
free 0, system-wide uuid 0, minimum percentage of free blocks 8, TIME
optimization

So it looks like start of ad12s1 is the same as ad12s1a.
On some better configured disks I see:
$ file -s /dev/ad6s1
/dev/ad6s1: x86 boot sector; partition 4: ID=0xa5, active, starthead 0,
startsector 0, 50000 sectors

Ultimately I would like to fix this so that I don't see labels on the
slices.


-- 
Andriy Gapon