install on multiple disks

[Ross Boylan]

What do I need to do to install grub to multiple drives so that if one drive fails and the one of the other becomes the "first" drive it will boot?

This would be with grub 1.96 backported to Debian Lenny; I've been looking at the current grub2 manual.  I have software RAID1 on partitions of disks.  Some disks are MSDOS partitioned and others GPT (with a bios_legacy partition).

The online manual is cryptic.  It suggests

grub-install /dev/sdb

might work but....

My /boot is on a separate partition, also known as /dev/md0 (this is sda1, sdb2, sdc2).  So, do I take the default --boot-directory=/boot, or do I need --boot-directory=/ because the partition has no /boot directory?  The issue here is that there are 2 separate things I need to specify: the location in which to install things now, with a running system, and where grub should look as it boots off the MBR.  I don't know which of these is --boot-directory, and obviously it can't be both.

My second concern, of course, is that the stuff installed in the boot record of sdb may refer to the second hard drive (hd1), but when I need it, I'll want (hd0).

I don't see any boot sector installation commands in the main command listings, nor do I see anything about grub-setup, though the manual mentions it several times.

Merry Christmas!

Ross Boylan