DISKTAB(5) File Formats Manual DISKTAB(5)NAME
disktab - disk description file
SYNOPSIS
#include <disktab.h>
DESCRIPTION
Disktab is a simple date base which describes disk geometries and disk partition characteristics. The format is patterned after the term-
cap(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 following list indicates the normal values stored for each disk entry.
Name Type Description
ns num Number of sectors per track
nt num Number of tracks per cylinder
nc num Total number of cylinders on the disk
b0 str Filename of block zero primary bootstrap for device
ba num Block size for partition `a' (bytes)
bd num Block size for partition `d' (bytes)
be num Block size for partition `e' (bytes)
bf num Block size for partition `f' (bytes)
bg num Block size for partition `g' (bytes)
bh num Block size for partition `h' (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)
ff num Fragment size for partition `f' (bytes)
fg num Fragment size for partition `g' (bytes)
fh num Fragment size for partition `h' (bytes)
pa num Size of partition `a' in sectors
pb num Size of partition `b' in sectors
pc num Size of partition `c' in sectors
pd num Size of partition `d' in sectors
pe num Size of partition `e' in sectors
pf num Size of partition `f' in sectors
pg num Size of partition `g' in sectors
ph num Size of partition `h' in sectors
se num Sector size in bytes (default 512)
sf bool supports bad144-style bad sector forwarding
so bool partition offsets in sectors
ty str Type of disk (e.g. removable, winchester)
Disktab entries may be automatically generated with the diskpart program.
FILES
/etc/disktab
SEE ALSO newfs(8), diskpart(8), getdiskbyname(3)BUGS
This file shouldn't exist, the information should be stored on each disk pack.
4.2 Berkeley Distribution May 17, 1986 DISKTAB(5)
Check Out this Related Man Page
DISKPART(8) BSD System Manager's Manual DISKPART(8)NAME
diskpart -- calculate default disk partition sizes
SYNOPSIS
diskpart [-d] [-p] [-s size] disk-type
DESCRIPTION
diskpart is used to calculate the disk partition sizes based on the default rules used at Berkeley.
Available options and operands:
-d An entry suitable for inclusion in the disk description file /etc/disktab is generated; for example, disktab(5).
-p Tables suitable for inclusion in a device driver are produced.
-s size The size of the disk may be limited to size with the -s option.
On disks that use bad144(8) type of bad-sector forwarding, space is normally left in the last partition on the disk for a bad sector forward-
ing table, although this space is not reflected in the tables produced. The space reserved is one track for the replicated copies of the ta-
ble and sufficient tracks to hold a pool of 126 sectors to which bad sectors are mapped. For more information, see bad144(8). The -s option
is intended for other controllers which reserve some space at the end of the disk for bad-sector replacements or other control areas, even if
not a multiple of cylinders.
The disk partition sizes are based on the total amount of space on the disk as given in the table below (all values are supplied in units of
sectors). The 'c' partition is, by convention, used to access the entire physical disk. The device driver tables include the space reserved
for the bad sector forwarding table in the 'c' partition; those used in the disktab and default formats exclude reserved tracks. In normal
operation, either the 'g' partition is used, or the 'd', 'e', and 'f' partitions are used. The 'g' and 'f' partitions are variable-sized,
occupying whatever space remains after allocation of the fixed sized partitions. If the disk is smaller than 20 Megabytes, then diskpart
aborts with the message ``disk too small, calculate by hand''.
Partition 20-60 MB 61-205 MB 206-355 MB 356+ MB
a 15884 15884 15884 15884
b 10032 33440 33440 66880
d 15884 15884 15884 15884
e unused 55936 55936 307200
h unused unused 291346 291346
If an unknown disk type is specified, diskpart will prompt for the required disk geometry information.
SEE ALSO disktab(5), bad144(8)HISTORY
The diskpart command appeared in 4.2BSD.
BUGS
Most default partition sizes are based on historical artifacts (like the RP06), and may result in unsatisfactory layouts.
When using the -d flag, alternative disk names are not included in the output.
BSD June 6, 1993 BSD