Updated: 2022/Sep/29

Please read Privacy Policy. It's for your privacy.

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

     diskpart - calculate default disk partition sizes

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

     -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

     -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
     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.

     disktab(5), bad144(8)

     The diskpart command appeared in 4.2BSD.

     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

NetBSD 10.99                     June 6, 1993                     NetBSD 10.99