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DISKPART(8)		FreeBSD	System Manager's Manual		   DISKPART(8)

     diskpart -- calculate default disk	partition sizes

     diskpart [-p] [-d]	[-s size] disk-type

     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 pro-

     -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

     On	disks that use bad144(8) type of bad-sector forwarding,	space is nor-
     mally 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

     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 opera-
     tion, either the `g' partition is used, or	the `d', `e', and `f' parti-
     tions 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.

     disktab(5), bad144(8)

     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 out-

     The diskpart command appeared in 4.2BSD.

4th Berkeley Distribution	 June 6, 1993	     4th Berkeley Distribution


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