Lost Boot Sector

tomdean tomdean at speakeasy.org
Thu May 10 17:21:57 UTC 2012

FreeBSD AMD64 9-stable up-to-data as of a week ago.  ASUS P9X79 
motherboard. (OC 4.2GHz)

I have 4 SATA disks.  (disk 0)500G windows 7 plus a (disk 1)windows 
mirror, (disk 2)500G FreeBSD, (disk 3)160G
backup.  I need windows for .NET, Gadgeteer, and uM-FPU.  (otherwise, 
... hot rock)

Windows stabbed a disk, I think.  After using windows, the next AM, I 
found the system with a US cursor on a black background.  When I booted 
with BIOS selector, I saw a windows update message go by.  The windows 7 
(disk 0) is not recognized by windows 7 after booting disk 1 via BIOS 
and selecting 'windows 7 secondary plex'.  So,
either disk 0 died or windows stabbed it (not unheard of).

I was using grub from an old linux installation.  Disk 2 is not bootable 
from BIOS - it tries but I get a running '#',
forever.  I booted the FreeBSD 9.0 RC2 live CD.  FreeBSD (disk 2) is 
still there (whew!) and looks intact.

disk 2 GPT:
0 GPT (456G)
1 linux-data (93G)  debian???
2 linux-swap (29G)
3 FreeBSD-boot (64k)
4 FreeBSD-ufs (338G)
5 FreeBSD-swap (4G) <== I need to increase this to 16G (== RAM)
- free (847M)

I plan to use BIOS boot, with FreeBSD as the default - no more auto boot 

disconnect all disks except (disk 2) - it will appear in BIOS as P0.
boot the 9.0 RC2 live CD
if pmbr and gptboot are on (disk 2) use those files, else use the live 
CD files

# gpart bootcode -b /boot/pmbr -p /boot/gptboot -i 3 /dev/ada0

I think this puts pmbr on (disk 2) boot sector and gptboot on partition 3.

Will this make the disk bootable?
And boot FreeBSD when selected from BIOS?

With only the windows 7 secondary plex disk connected, it boots.

Tom Dean

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