Path: utzoo!mnetor!uunet!lll-winken!lll-tis!mordor!sri-spam!ames!pacbell!att-ih!cuuxb!dlm
From: dlm@cuuxb.ATT.COM (Dennis L. Mumaugh)
Newsgroups: comp.unix.wizards
Subject: Re: Disk maps on unix disks (a standard???)
Message-ID: <1766@cuuxb.ATT.COM>
Date: 25 Apr 88 22:52:54 GMT
References: <355@tandem.UUCP
Reply-To: dlm@cuuxb.UUCP (Dennis L. Mumaugh)
Organization: ATT Data Systems Group, Lisle, Ill.
Lines: 24
Keywords: vtoc
Summary: /etc/fmthard on system V

In article <355@tandem.UUCP   narayan@tandem.UUCP (Narayan Mohanram) writes:
  In most unix systems, when one makes a file system via an
  FSCK, they have to dig up the manual for the disk type to
  see how the disc driver has laid out the disk (the various
  partions sizes, and starting point). Has any-one come up
  with a standard for putting these partition map info on
  the front a disk on a super-super block so to speak. Then
  one can mount a disk pack on any unix system, and read it.
  The drivers/unix can get the info from the front of the
  disk.

On UNIX System V for the ATT 3B2/5/15/4000 the second  sector  on
the  disk  is  the VOLUME TABLE OF CONTENTS (vtoc).  It describes
the disk's partitioning.  The first 100 sectors of any disk (hard
or  floppy)  are the boot sectors and excluded from the unix file
system.  One "partition" ususually 6 included the whole disk  but
of  course  one  couldn't mount it as the disk didn't look like a
real filesystem.

There were some pre-defined vtocs for "default" or naive users.


-- 
=Dennis L. Mumaugh
 Lisle, IL       ...!{ihnp4,cbosgd,lll-crg}!cuuxb!dlm