[plug] Root/Boot on Software RAID

[Grahame Bowland]

On 17 Sep 2001 11:53:23 +0800, AWoodley at IINet.net.au wrote:
> G'Day,
>     I'm in the process of setting up a proxy server for a school, the main
> objective being that it will stay running with a minimum of maintainence.
> To this end I intend to set up a RAID 1 for /, /usr, /home and RAID 0 for
> /var. However, I'm having difficulty getting the thing to boot using the
> RAID device as /. I've followed the steps outlined in the Software RAID
> Howto on setting up a root RAID using only two drives (setting the current
> root partition as a failed disk in the raidtab and using the RAID device in
> degraded mode). All RAID devices are detected at boot when using a standard
> partition as root, however the kernel complains that it cannot read the
> superblock when trying to boot with root=/dev/md0.
> 
> I have an initrd image which includes the raid1 and ext2 modules and the
> fstab on the raid device has been modified to use /dev/md0 as root, however
> I feel that the problem is occuring before the fstab is read.
> 
> I'm using Debian Woody with the 2.4 kernel, the hard-drives are the same
> specs and set up as the masters on ide0 and ide1 buses.
> 
> Any help would be greatly appreciated, as well as any suggestions of other
> ways of ensuring the statbility of the system.

Several of our servers at UCS use RAID-1 as the root device. The easiest
way to solve problems like this is to lower the number of things that
could be going wrong:
 - recompile your kernel with raid1 and ext2 compiled in, 
   not as modules in case this is the problem. You're going to want
   these in the kernel anyway, so there's no special reason to have 
   them as modules
 - make sure you changed the partition type of all RAID 
   partitions to fd (Linux RAID autodetect)

Lilo in debian definitely knows about RAID; as far as I know all recent
lilo releases do. Nothing has to be done to lilo to make it work on
Potato, so I'm guessing Woody will be fine.

Good luck,
Grahame

-- 
Grahame Bowland, Network and Systems Administrator
University Communications Services, The University of Western Australia
Phone: +61 8 9380 1175