DISKPART

Section: Maintenance Commands (8)
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BSD mandoc
BSD 4  

NAME

diskpart - calculate default disk partition sizes  

SYNOPSIS

diskpart [-p ] [-d ] [-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:

-p
Tables suitable for inclusion in a device driver are produced.
-d
An entry suitable for inclusion in the disk description file /etc/disktab is generated; for example, disktab(5).
-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 forwarding table, although this space is not reflected in the tables produced. 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 -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)  

BUGS

Most default partition sizes are based on historical artifacts (like the RP06), and may result in unsatisfactory layouts.

When using the -d flag, alternate disk names are not included in the output.  

HISTORY

The diskpart command appeared in BSD 4.2


 

Index

NAME
SYNOPSIS
DESCRIPTION
SEE ALSO
BUGS
HISTORY

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Time: 06:25:27 GMT, May 19, 2025