Looking for rationale of fs naming conventions

Kirk McKusick mckusick at mckusick.com
Fri Sep 4 10:25:15 AEST 1998

	From: "User Rdkeys Robert D. Keys" <rdkeys at seedlab1.cropsci.ncsu.edu>
	Subject: Re: Looking for rationale of fs naming conventions
	In-Reply-To: <199809011719.MAA15499 at fudge.uchicago.edu>
		from Eric Fischer at "Sep 1, 98 12:19:07 pm"
	To: eric at fudge.uchicago.edu (Eric Fischer)
	Date: Tue, 1 Sep 1998 14:16:04 -0400 (EDT)
	Cc: rdkeys at seedlab1.cropsci.ncsu.edu (User RDKEYS Robert D. Keys),
		pups at minnie.cs.adfa.oz.au

	Thanks Eric....  that sort of discussion makes my day, and feeds my
	woefully short history folder, nicely!  Does anything in print cover
	this sort of thing in one place?

	So much to learn....

	Bob Keys

The `diskpart' utility was used in 4.4BSD to organize disk partitions.
Its manual page tries to rationalize the use of partitions. I enclose
it below in case you do not have access to it.

	Kirk McKusick


DISKPART(8)               BSD 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 de-
     fault 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 op-

     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 re-
     quired 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                                2

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