*BSD News Article 10778


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Path: sserve!manuel.anu.edu.au!munnari.oz.au!hp9000.csc.cuhk.hk!saimiri.primate.wisc.edu!caen!uwm.edu!cs.utexas.edu!uunet!infoserv!lila!dorsey
From: dorsey@lila.com (Bill Dorsey)
Subject: Re: /usr won't mount
Message-ID: <C1x7oJ.Kv@lila.com>
Sender: usenet@lila.com
Reply-To: dorsey@lila.com
Organization: Yoyodyne Propulsion Systems, Inc.
References: <C1vEFJ.2oJ@lila.com>
Date: Thu, 4 Feb 1993 10:55:31 GMT
Lines: 27

Earlier I posted an article detailing problems I had installing the new patch-
kit (to patch 75) on my system.  Mount was failing on my /usr filesystem com-
plaining of a bad magic number in the superblock.  Well, I think I managed to
track down the problem.

When my disk was last partitioned, the individual who partitioned it (who shall
remain nameless, but it wasn't me) did not align the partitions with cylinder
boundaries.  For some reason, the original wd.c driver didn't seem to mind and
the system worked fine for many months.  Upon installing the patches to wd.c
(I forget the patch number) that made it work with partitions that aren't aligned
with cylinder boundaries, the system would fail to mount the affected filesystems.

My bet is that the original code may have rounded or otherwise munged the starting
and ending block pointers of the filesystems created on partitions not aligned with
cylinder boundaries.  When I installed the patch to wd.c, it presumably calculated
the correct starting and ending block pointers and then failed to mount because it
found something other than a superblock at the offset it expected to find the
superblock.

Nothing a few hours of time spent backing up and restoring my system couldn't fix.

---
Bill Dorsey      "Most people mistake law for justice and authority for
dorsey@lila.com   liberty.  You will hear them talk of 'liberty under law,'
PGP 2.x public    and they are content to see it so deep under the law that
key on request    it is completely obliterated." -- Herbert Spencer