[lug] RAID redundancy with boot sectors?

D. Stimits stimits at comcast.net
Sat Nov 25 16:09:53 MST 2006

I'm curious about something with software RAID on linux. You can easily 
make partitions redundant by using something like RAID 1/5/10 instead of 
just partitioning directly on a drive. What's the right way to back up 
the boot sector itself? Using software RAID 10 as an example, I believe 
that since the BIOS and standard non-RAID controllers do not have any 
knowledge of RAID, that there is no possibility of automatically 
including the boot sector within the RAID. Would installing the boot 
record onto the MBR of the first physical drive, then doing a dd of a 
512 byte block to all other RAID drives at least make it possible to 
yank the first drive out and move another drive into its place in order 
to get boot ability back? Or would that also mess up the RAID itself 
(and assuming LVM is being used, LVM too)? I'm just thinking that part 
of the RAID data or LVM data could make the MBR itself different from 
one physical drive to the next. I could imagine simply keeping a 512 
byte dd copy of the MBR of each drive on a floppy and restoring via dd 
if the drive ever got replaced.

D. Stimits, stimits AT comcast DOT net

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