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