diskpart - calculate default disk partition sizes
/usr/sbin/diskpart [ -p ] [ -d ] disk-type
Diskpart is used to calculate the disk partition sizes based on the default rules used at
Berkeley. If the -p option is supplied, tables suitable for inclusion in a device driver
are produced. If the -d option is supplied, an entry suitable for inclusion in the disk
description file /etc/disktab is generated; c.f. disktab(5). On disks that use
bad144-style bad-sector forwarding, space is left in the last partition on the disk for a
bad sector forwarding table. The space reserved is one track for the replicated copies of
the table and sufficient tracks to hold a pool of 126 sectors to which bad sectors are
mapped. For more information, see bad144(8).
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 512 byte 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
Certain default partition sizes are based on historical artifacts (e.g. RP06), and may
result in unsatisfactory layouts.
When using the -d flag, alternate disk names are not included in the output.
4th Berkeley Distribution November 17, 1996 DISKPART(8)