[]Hi,
[snip]
The boot loader is grub and I want both /boot and / raided.
In the event of a failure of hda I would like the system to switch to hdc. This works fine. However what I have had problems with is if the system reboots. If /dev/hda is unavailable I no longer have a disk with a boot sector set up correctly. Unless I have a floppy or CDROM with a boot loader the system will not come up.
one possible solution would be to use lilo. lilo is capable of booting from md raid1 arrays. look at lilo.conf(5) manpage for 'raid-extra-boot' in 'GLOBAL OPTIONS'. i use it on most of my maschines. AFAIK grub is not able to boot from /dev/mdX.
When using raid-extra-boot, lilo treats second disk as bios #0x81, 3rd disk as bios #0x82 and so on. That to say - if your first disk fails and BIOS will substitute second disk in place of first, making it 0x80 instead of 0x81, lilo will not boot too, exactly in a way why grub installed into /dev/hdb (that was e.g. temporarily plugged into another machine just to make it bootable etc) does not want to boot from it when it will be /dev/hda again (when returned back into it's own machine).
Instead of using raid-extra-boot, IMHO, it is more safe to install lilo into the raid array instead of the MBR, and use standard MBR to boot from active partition. But granted, lilo's raid-extra-boot will work around different disk layouts, while lilo on raid with standard MBR will not.
/mjt
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