grub-install to mdp-style RAID1 array?

Hello,

I have a server which is currently still running on 1 of 2 drives. The server originally had /boot, /, and swap partitions set up as RAID1 md devices, ie, matching partitions set up on each drive, then RAID1 md arrays created. The other drive has failed, so I would like to create a new mdp-style array with 2 other drives and "migrate" the server to the new array.

I've gotten the mdp-style array created with no problem and am also able (by adding the array's info to /etc/mdadm.conf) to get FC5 to start the array before trying to init. (my initrd.img already has the RAID1 module in it). So I think I'm pretty close to being able to get this working. The one thing that seems to remain is getting the GRUB bootloader installed onto the mdp RAID device, goal being to be able to boot from the mdp RAID device.

The command I used to create the array was:

# mdadm --create /dev/mdpraid --auto=mdp --level=1 --raid-devices=2 /dev/hdi /dev/hdk

which works fine, the raid device gets created without any problem. I've also tried this creating mdp arrays with more standard names for the device like /dev/md_d0 and /dev/md/d0.

I've mke2fs'd the mdpraid1 partition (first partition of the RAID device) for the /boot filesystem, and copied /boot/* from the drive the system is currently actually running on, then tried various ways of running grub-install. The /boot filesystem on the new array is mounted at /raidtest/boot, where /raidtest would be the new root filesystem on /dev/mdpraid3, mounted here while running the current root filesystem.

I've tried these things:

editing /raidtest/boot/grub/device.map to define (hd0) as /dev/mdpraid editing /raidtest/boot/grub/device.map to define (hd0) as /dev/md_d0 editing /raidtest/boot/grub/device.map to define (hd0) as /dev/md/d0

(the last two when that's what the test device was created as)
---
running grub-install:

# grub-install --root-directory=/raidtest /dev/mdpraid
response:
/dev/hdi does not have any corresponding BIOS drive.
---
running interactive grub shell:

GNU GRUB version 0.95 (640K lower / 3072K upper memory)

[ Minimal BASH-like line editing is supported. For the first word, TAB
lists possible command completions. Anywhere else TAB lists the
possible
completions of a device/filename.]

grub> device (hd0) /dev/mdpraid

grub> root (hd0, <- tab completion attempt to see what it will say:
Possible partitions are:

   Partition num: 0,  Filesystem type is ext2fs, partition type 0x83
   Partition num: 1,  Filesystem type unknown, partition type 0x82
   Partition num: 2,  Filesystem type is ext2fs, partition type 0x83

grub> root (hd0,0)
Filesystem type is ext2fs, partition type 0x83

grub> setup

Error 11: Unrecognized device string

---

I was less expectant of the first method (grub-install) to work, but I can't seem to coax the interactive shell to 'setup', regardless of what I name the md device. Just for the heck of it, I even tried 'mknod -m 600 /dev/hdz b 254 0' to create another device node with a /dev/hd*-style name but pointing to the current block major/minor of the
/dev/mdpraid device, to try to fool GRUB into accepting the device
name, but it gives the same error message (Error 11).

Any suggestions? Am I going to have to manually install the bootloader to each member drive as is typically necessary with md-style RAID1 devices so that either drive is bootable?

Neil helped me on a scenario like this a few years back when I was still using LILO and running a patched 2.4 kernel, but things seem rather different nowadays with 2.6.16 etc. and GRUB. Any advice anyone can offer would be very much appreciated.

Thanks,
Vince

Uh, turns out I wasn't using the right syntax....

typing this instead worked:

grub> setup (hd0)

I can now boot from the partitioned MD device. woo-hoo!

Now to see if I can pull the 1st drive and boot from the 2nd drive in the array.

Vince