Re: recent kernel upgrades damage mbr

Gene Heskett wrote:

On Wednesday 18 June 2008, Mikkel L. Ellertson wrote:

This is not going to help, because the old MBR will be pointing to
the wrong location for stage 1.5, so you will get an error on boot.
Remember, the part of GRub that is in the MBR loads from a fixed
disk location. It does not read the file system. So, unless stage
1.5 is in the same place on the disk, (head, cylinder, sector) it is
not going to be able to load it.

Your best bet is to fix the device map, and run grub-install.

Mikkel

I have Mikkel, twice, and grub-install (or one of its friends) overwrote it both times. Lets just say it was "educational". I now have backups under other names there.

--------device.map--------
# this device map was generated by anaconda
(hd0)     /dev/sdb
--------------------------
No mention of any other drives seems to be allowed, and there are 2 others.

This is strange, because grub-install is not supposed to change the device map unless you use the --recheck option.

Also NDI why it says Anaconda, cuz Anaconda hasn't been exec'ed on this box since last February when (I think nvidia blobs had something to do with it) when something, for the 2nd time in 3 months, wiped the mbr from the boot drive. Now I'm on an old ATI card running the radeon driver, and no further problem (knock on wood). Maybe, if and when I get around to building another box, the new mobo's bios won't be so fscking brain dead and I won't have to screw around with this anymore.

I forgot - one other thing that may help is to change /etc/sysconfig/grub to match what you need in the device map. That may be where the changed device map is coming from.

While we're on the subject of mbr's, how big is it? The first 512 bytes of the one I just saved is virtually empty. So I overwrote it with a 4kb version, but that is bearing some resemblance to a list of inodes.

The MBR, including the partition table is normally 512 bytes. If it is empty, then you may be using the wrong device. Did you use /dev/hda1, and not /dev/hda? Writing 4kb can lead to file system corruption.

Mikkel
--

  Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!

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