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DISKTAB(5) File Formats Manual DISKTAB(5)

disktab — disk description file

disktab is a simple database which describes disk geometries and disk partition characteristics. It is used to initialize the disk label on the disk. The format is patterned after the termcap(5) terminal database. Entries in disktab consist of a number of colon (‘:’) separated fields. The first entry for each disk gives the names which are known for the disk, separated by “|” characters. The last name given should be a long name fully identifying the disk.

The following list indicates the normal values stored for each disk entry:

dt str Type of controller (e.g., SMD, ESDI, floppy).
ns num Number of sectors per track.
nt num Number of tracks per cylinder.
nc num Total number of cylinders on the disk.
sc num Number of sectors per cylinder (default: ns*nt).
su num Number of sectors per unit (default: sc*nc).
se num Sector size in bytes (default: DEV_BSIZE).

ba num Block size for partition “a” (bytes).
bd num Block size for partition “d” (bytes).
be num Block size for partition “e” (bytes).
[...]
bp num Block size for partition “p” (bytes).

fa num Fragment size for partition “a” (bytes).
fd num Fragment size for partition “d” (bytes).
fe num Fragment size for partition “e” (bytes).
[...]
fp num Fragment size for partition “p” (bytes).

oa num Offset of partition “a” (sectors).
ob num Offset of partition “b” (sectors).
oc num Offset of partition “c” (sectors).
[...]
op num Offset of partition “p” (sectors).

pa num Size of partition “a” (sectors).
pb num Size of partition “b” (sectors).
pc num Size of partition “c” (sectors).
[...]
pp num Size of partition “p” (sectors).

ta str Type of partition “a” (4.2BSD, swap, etc.).
tb str Type of partition “b”.
tc str Type of partition “c”.
[...]
tp str Type of partition “p”.

/etc/disktab
 

getdiskbyname(3), disklabel(5), disklabel(8), newfs(8)

The disktab description file appeared in 4.2BSD.

November 7, 2022 OpenBSD-current