Can grub be installed on a md array?

Rashkae ubuntu at
Wed Oct 15 17:07:57 UTC 2008

John Hubbard wrote:
> I am trying to set up my system (8.04 server) with software raid.  I got 
> most of the way through the install and then it failed to install grub.  
> I tried installing lilo and that failed as well.  I feel like the 
> problem is that my /boot partition is part of a 4 disk raid 5 array.  Is 
> it possible to install your boot loader onto a raid array?  When setting 
> up a partition on a raid array, there is no option to make the partition 
> bootable.  I guess this makes sense but the question is how do I get 
> around this?  Does the logical partition on each of the disks that makes 
> up the /boot raid need to be made bootable?  Does just one of those 
> partitions need to be made bootable? 

Grub, or any bootloader for that matter, needs to read the Linux Kernel
from /boot.  Before the kernel loads, there is no software raid.  With
no software raid, one can't boot from a Raid array.  Classic chicken and
egg scenario, and it will affect any software raid solution.  Therefore,
you need a separate partition for /boot when using Raid 5.  If you want
the /boot partition to be fault tolerant, create 2 partitions and use
Raid 1.  (You don't need software raid to work for read access to a
mirror array, since you can just read the data off the single drive as
though it were not a raid device.)

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