While running OpenBSD, I decided to try its ext2fs.  I mounted my Linux
root partition r/w from OpenBSD, did not write anything and immediately
unmounted it.  Then I tried to mount it again from a "permanent" mount
point, but got an I/O Error.

Next, I rebooted the Sparc from OpenBSD 3.4 to SuSE GNU/Linux 7.3.  Or
so thought I was going to do.  SILO worked fine, but it couldn't find
/etc/silo.conf (boot entries).  Tried to boot by manually entering the
kernel path, but no dice.  I booted into rescue mode and did an fsck on
the root filesystem, and the first major problem is _no_ root directory
and not surprising no lost+found for fsck to put the remnants of the
root filesystem.  There's over a dozen inodes with bad counts, etc.

It turns out the damage wasn't too bad.  Just had to move all the orphan
directories from lost+found into the new root directory and rename them
from their inode based name back to their original names such as
bin. lib, etc, ,,.  After the simple repair, SuSE GNU/Linux 7.3 boots
fine from SILO on the hard drive again.

What probably caused this problem:  On Sparc at least, Linux will
create partitions of non-integral cylinder size.  OpenBSD insists on
partitions that are aligned on cylinder boundaries.  I used Linux to
create the disk's partition table and adjusted the partitions to be used
by OpenBSD to be cylinder aligned, wasting a few sectors.  I forgot that
SuSE's root partition wasn't cylinder aligned like OpenBSD likes.  My
guess is the partition alignment or simply mounting r/w was the problem.
Next, I'll try to test OpenBSD ext2fs on an ext2 partition that I don't
care if I lose.

One other note about OpenBSD:  The installer insists on using the
first partition (sd0a = sda1) on the drive as root and the second
partition (sd0b = sda2) on the drive as swap.  I couldn't see an easy
way around this limitation.  After installation, it shouldn't be hard to
move root and swap to other partitions so long as root stays within the
Sun OBP booting limit of 1GB.  (Newer OBP may not be quite so limiting.)

Sincerely,

Ken Fuchs <kfuchs at winternet.com>



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