Path: utzoo!attcan!uunet!legato!mojo
From: mojo@legato (Joseph Moran)
Newsgroups: comp.unix.wizards
Subject: Re: Trashed Disk Labels Under Sun OS 3.5
Message-ID: <919@legato.LEGATO.COM>
Date: 11 Aug 89 04:58:23 GMT
References: <5253@wiley.UUCP> <18969@mimsy.UUCP>
Reply-To: mojo@legato (Joseph Moran)
Organization: Legato Systems, Inc., Palo Alto, CA
Lines: 20

In article <18969@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes:
>SunOS starts swap space at sector 0 of the swapon partition.  The label
>is in disk sector 0.  Thus, SunOS will swap on top of the label if the
>partition begins at disk sector 0.

SunOS 3.x and earlier followed the conventions of 4.2 BSD for
allocating swap space which resulted in disk labels and boot blocks
getting trashed if you swapped onto a partition that started at
cylinder 0 (typically `a' and `c').

SunOS 4.0 and greater has a totally different VM system.  During this
rewrite, code was added to skip over the first part of each swap device
to prevent the "disk label overwrite" problem.

Joseph Moran
Legato Systems, Inc.
260 Sheridan Avenue
Palo Alto, CA  94306
(415) 329-7886
mojo@Legato.COM or {sun,uunet}!legato!mojo