NAME

disktab − disk description file

SYNOPSIS

#include <sys/disktab.h>

DESCRIPTION

Disktab is a simple data base which describes disk geometries and disk partition characteristics.  The format is patterned after the termcap(5) terminal data base.  Entries in disktab consist of a number of ‘:’ 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 disk(8) program writes this information to the label area of a disk when it is initialized.  The getdiskbyname(3) and getdiskbydev(3) routines may be used to read this information from the data base or disk label respectively.

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

 NameType Description
tystrType of disk (e.g. removeable_rw_optical)
nsnumNumber of sectors per track
ntnumNumber of tracks per cylinder
ncnumTotal number of cylinders on the disk
pa-hnumBase sector number of partition [a-h]
sa-hnumSize of partition [a-h] (sectors)
ba-hnumBlock size for partition [a-h] (bytes)
fa-hnumFragment size for partition [a-h] (bytes)
ca-hnumPartition "cylinders-per-group" for newfs
da-hnumPartition density ("bytes-per-inode") for newfs
ra-hnumPartition "minfree" for newfs
oa-hstrPartition optimization ("space" or "time") for newfs
ia-hboolRun newfs(8) on partition during initialization with disk(8)
ma-hstrPartition mount point name
aa-hnumPartition auto-mount on insert
ta-hstrPartition file system type ("4.3BSD", "sound" etc.)
rmnumRotational speed in rpm (3600 default)
ssnumSector size in bytes
fpnumNumber of sectors in "front porch" of disk
bpnumNumber of sectors in "back porch" of disk
ngnumNumber of alternate groups on the disk
gsnumNumber of sectors per alternate group
ganumNumber of alternate sectors per alternate group
aonumSector offset of alternates in alternate group
osstrName of file to boot from
z0-1numLocations (block number) of first level boot code
hnstrHostname
rocharRead only root partition (e.g. ’a’)
rwcharRead/write partition (e.g. ’b’)

FILES

/etc/disktab

SEE ALSO

disk(8), newfs(8), getdiskbyname(3), getdiskbydev(3)

4.2 Berkeley Distribution  —  May 17, 1986