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2012-11-14

FreeBSD Disk Labels and Mapping

You may notice that in /etc/fstab that filesystems are mounted from "/dev/ufs/" you think to yourself "This is strange, I don't think there are any drive types recognized in freebsd as /dev/ufs".

What's actually happened here is that there has been a permanent label created on the FreeBSD machine using either tunefs or newfs.

The main question you may ask is "How to I figure out where the drives are actually mapped to?". To do that all you need to do is run the following command:
glabel status
# glabel status
      Name  Status  Components
    ufs/DATA3     N/A  aacd1p1
     ufs/ROOT     N/A  aacd0s1a
   label/SWAP     N/A  aacd0s2b
    ufs/DATA2     N/A  aacd0s2e

You can now see where the devices are mapped to physically and then use fdisk to find out further information about these disks.
# fdisk -s aacd0
/dev/aacd0: 17860 cyl 255 hd 63 sec
Part        Start        Size Type Flags
   1:          63     1638567 0xa5 0x80
   2:     1638630   281282085 0xa5 0x00
   3:   282920715     4000185 0x0b 0x00
# fdisk -s aacd1
/dev/aacd1: 196461 cyl 255 hd 63 sec
Part        Start        Size Type Flags
   1:           1  3156150271 0xee 0x00

Further information can be found at the following link:
http://www.freebsd.org/doc/handbook/geom-glabel.html

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