This tip deals somewhat with Solaris, though moreso with FreeBSD.
On a Solaris host, to quickly determine how a hard disk may be carved up,
one can simply run prtvtoc against the device:
sunbox [0] /usr/bin/uname -aOn a Solaris host, to quickly determine how a hard disk may be carved up,
one can simply run prtvtoc against the device:
SunOS sunbox 5.10 Generic_118855-14 i86pc i386 i86pc
sunbox [0] /usr/sbin/prtvtoc /dev/dsk/c1t0d0s2
* /dev/dsk/c1t0d0s2 partition map
*
* Dimensions:
* 512 bytes/sector
* 63 sectors/track
* 255 tracks/cylinder
* 16065 sectors/cylinder
* 8921 cylinders
* 8919 accessible cylinders
*
* Flags:
* 1: unmountable
* 10: read-only
*
* First Sector Last
* Partition Tag Flags Sector Count Sector Mount Directory
0 2 00 16803990 4192965 20996954 /
1 3 01 16065 8401995 8418059
2 5 00 0 143283735 143283734
3 4 00 20996955 16787925 37784879 /usr
4 7 00 12611025 4192965 16803989 /var
5 8 00 8418060 4192965 12611024 /export/home
6 0 00 37784880 105498855 143283734 /bitbucket
8 1 01 0 16065 16064
As seen above, this was run on a Solaris x86 box, however the output
is nearly identical for sparc based hosts. When used without any options,
prtvtoc will print out the VTOC (volume table of contents) with additional
header information. To remove this information, printing only the VTOC,
supply option -h to prtvtoc.
In dealing with FreeBSD, unlike Solaris systems, a usable disk would both
contain slices and partitions. Before proceeding, clarification between
slices and partitions are necessary. A slice is a division of a disk
(4 potential slices), composed of contiguous sectors into which partitions
are created. A partition is a logical division of a slice and used in
dealing with filesystems. To determine the various slices of a device
residing at da0, one would use the fdisk command:
bsdbox [0] /usr/bin/uname -a
FreeBSD bsdbox 5.4-RELEASE FreeBSD 5.4-RELEASE #0: Mon May 8 11:23:06 EDT 2006
root@bsdbox:/usr/src/sys/i386/compile/SYSENG. i386
bsdbox [0] /sbin/fdisk /dev/da0
******* Working on device /dev/da0 *******
parameters extracted from in-core disklabel are:
cylinders=8924 heads=255 sectors/track=63 (16065 blks/cyl)
Figures below won't work with BIOS for partitions not in cyl 1
parameters to be used for BIOS calculations are:
cylinders=8924 heads=255 sectors/track=63 (16065 blks/cyl)
Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
start 63, size 143363997 (70001 Meg), flag 80 (active)
beg: cyl 0/ head 1/ sector 1;
end: cyl 1023/ head 254/ sector 63
The data for partition 2 is:
The data for partition 3 is:
The data for partition 4 is:
In the above, device da0 is seen to have only a single configured slice
(weirdly identified as a partition), that being slice 1. For a summarized
view of this information, once could pass -s to fdisk:
bsdbox [0] /sbin/fdisk -s /dev/da0
/dev/da0: 8924 cyl 255 hd 63 sec
Part Start Size Type Flags
1: 63 143363997 0xa5 0x80
Now that the configured slices are known, it is possible to determine
how those slices are carved up into partitions. With the same example as
above, the partitions configured on device da0 slice 1 can be determined
with bsdlabel (or disklabel, which is hard linked to bsdlabel):
bsdbox [0] /sbin/bsdlabel -A /dev/da0s1
# /dev/da0s1:
type: SCSI
disk: da0s1
label:
flags:
bytes/sector: 512
sectors/track: 63
tracks/cylinder: 255
sectors/cylinder: 16065
cylinders: 8924
sectors/unit: 143374650
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]
a: 2097152 0 4.2BSD 2048 16384 28552
b: 8388608 2097152 swap
c: 143363997 0 unused 0 0 # "raw" part, don't edit
d: 10485760 10485760 4.2BSD 2048 16384 28552
e: 2097152 20971520 4.2BSD 2048 16384 28552
f: 4194304 23068672 4.2BSD 2048 16384 28552
g: 2097152 27262976 4.2BSD 2048 16384 28552
h: 114003869 29360128 4.2BSD 2048 16384 28552
The output from bsdlabel is very similar to prtvtoc in the output it
gives, with the exception of identifying which partitions each device
was last mounted at. With the -A option, bsdlabel prints out full
header information, similar to prtvtoc without any options. To only
display how the device is partitioned, without the header information,
simply execute bsdlabel with the device being the only option. Of note,
just as in Solaris where slice 2 is treated specially (as it is the
length of the entire disk), in FreeBSD, partition c is the same.
