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Date:      Mon, 05 Jun 2000 09:26:41 +0000
From:      Mark Ovens <Mark.Ovens@uk.radan.com>
To:        questions@freebsd.org
Subject:   PC won't boot, Trashed partition table? Help required
Message-ID:  <393B7251.A1A21923@uk.radan.com>

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Apologies if this is rather long but I've lost 'net access at home so am
sending this from work and want to include as much info as I can since I
can't check things.

My PC will no longer boot due, I believe, to a trashed partition table.

I triple boot Win95, NT4, Freebsd 4-STABLE using the NT boot manager.
The system is spread over 2 disks:

	Disk 0  512MB FAT - Win95
		~320MB UFS - /, var, swap
		rest of disk is NTFS in an extended partition

	Disk 1
		Whole disk is UFS, /usr (*not* dangerously dedicated)

To allow FreeBSD to boot from the NT loader I copy /boot/boot1 to
C:\BOOTSECT.BSD and add an entry to C:\BOOT.INI. This has been set up
this way for years.

After doing a make world I check if /boot/boot1 has changed by
diff(1)'ing it against C:\BOOTSECT.BSD and if different copying the
former to the latter.

Last night I did this (copied boot1) and re-booted. I have a habit of
selecting FreeBSD from the NT menu and hitting RETRUN 3 times to start
it booting and bypass the "twirling baton" and 10-second countdown.
Instead of booting I saw:

	F5 Drive 1

	Default F5

	_

It took me a couple of minutes to realize that I'd copied boot0, not
boot1. OK, just re-boot and copy the old BOOTSECT.BSD back (yes, I'd
backed it up), however on reboot, instead of the NT loader menu I just
got the "F5 Drive 1" display and no boot. It took a while to realize
that the FreeBSD boot manager remembers the last partition booted and
the only place it can store this info is in the MBR, so it had written a
copy of itself to the MBR.

No problem, just boot from the NT setup disks, select Repair and tell it
to repair the boot sector (the NT equivalent of FDISK /MBR). NT
complained that it couldn't find a valid NT install to repair, unless I
had the Emergency Repair Disk (I had made one, but can't find it :( ).

Booting from a DOS floppy resulted in "Invalid drive specification" when
trying to change to C:.

I booted from another floppy which has the command line version of
Partition Magic on it. PM saw the whole of the first disk as free space
(yes it can recognize UFS partitions).

The only option left was to FDISK /MBR, but now all I get is "PRESS A
KEY TO REBOOT" when booting from the HD.

All this suggests that the partition table is trashed, but why? Surely
boot0 should only affect the MBR, not the partition table.

Any idea what has happened here?

Is it the partition table that is trashed?

Is there a way of recovering without having to re-install everything?

Can anyone help me here please?

Please Cc: me as I've no access to my list e-mail at the moment.

TIA.


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