Pooched MBR trying to turn DMA on
 

I'm running Debian (kernel 2.4.21) on a Dell Optiplex GX Pro and know just enough to be very dangerous. :(

The disk seemed a bit sluggish, so after a little research, I tried turning on DMA on the boot drive with:
hdparm -d1 /dev/hda

Things were OK immediately afterwards. hdparm -Tt showed a 50% improvement. I made happy noises.

Shutdown and now won't boot. After BIOS messages, it sits at a text-mode GRUB message (not a prompt - system is unresponsive; not the GRUB menu - just the words GRUB).

This system won't boot from floppy or CD, so I'm hosed.

Hoping to recover all the filesystems on the disk. I was thinking I would pop the drive into another machine running the same distro and try doing a grub-install.

Good idea? If not, any other suggestions?

Will the drive "remember" it's set to DMA?

Thanks in advance for any advice!

john

"Will the drive "remember" it's set to DMA? "

No. Rebooting will clear that.

"Hoping to recover all the filesystems on the disk. I was thinking I would pop the drive into another machine running the same distro and try doing a grub-install.

Good idea? If not, any other suggestions?"

It is easier to use a rescue CD.

Boot a rescue CD. If it is knoppix then umount your / partition after you boot. Other rescue CDs don't have to be umount the / partition. Assuming that your / partition is /dev/hda3 and the file system type is ext3 then do:
umount /dev/hda3

fsck -t ext3 /dev/hda3
Answer y to everything that fsck asks.

mkdir /horse
mount -t ext3 /dev/hda3 /horse
chroot /horse
grub-install /dev/hda
shutdown -r now


-----------------------------
Steve Stites

Follow up
 

Jailbait - thanks for the suggestions.

Multiple problems compounded the original one. I spent the last couple days rebuilding the system.

Just wanted to let you know I appreciated the help.