If I use the Debian Stable (Squeeze) Installer to install Debian, booting from a RAID1 pair of drives, does it write grub to the MBR of both drives - if not, how should I best protect against a drive failure - if I just clone the MBR won't it still point to the failed device?
Not sure if the installer does it by default, but if (once the system is booted) you run:
# dpkg-reconfigure -plow grub-pc
just hit enter until you're prompted for "GRUB install devices", then you can select the MBRs of both drives.
Here is a screenshot of the relevant screen in Debian Jessie (8.3), with GRUB2 version
2.02~beta2-22+deb8u1. This shows the setup of my computer, which has two drives (
/dev/sdb) in a RAID 1 configuration (
/dev/md1), and two other drives (
/dev/sdd) in a RAID 1 configuration (
If you install Grub legacy, then it's only installed on the one boot disk. You can add it to the second disk's MBR by running
grub-install /dev/sdb (assuming that your second disk is
/dev/sdb). Make sure that in both cases, Grub reads from the first BIOS disk (you may need to tweak
/boot/grub/device.map for that). If one of the two disks fails, whichever disk is left will be the first BIOS disk.
You can install Grub2 on Debian squeeze, and I recommend that if you have any sort of nontrivial setup such as RAID. Grub2 has the advantage that you can put your whole system on LVM, you don't need a non-LVM
/boot partition. As far as I know, the squeeze installer supports installations over RAID+LVM with grub2 (you may need to coerce it a little not to create a separate