Re: software mirroring of boot drive

[Ed Wilts <ewilts ewilts org>]

On Fri, Jun 25, 2004 at 09:16:52AM -0700, Grunloh, Robert wrote:
> I'm trying to set up a rhel 3 server with 2 18gig scsi drives, where each
> disk has the entire os and mirrors the other, so that we have no downtime if
> either drive fails. The machine doesn't have hardware raid, so I've
> partitioned it as sda1 & sdb1 /boot and sda2 & sdb2 /  and then created md0
> and md1 during the install (raid 1). From what I can tell everything is
> working once booted.
> 
> However if, as a test, I tell the scsi card's bios to boot off of the 2nd
> drive it just hangs (no errors) before the grub menu appears. Same behavior
> if I unplug the first drive. If I unplug the 2nd drive it boots ok but
> complains about degraded mode, as expected.
> 
> I suspect the partitions are mirrored but grub isn't properly installed on
> the second drive's MBR or isn't aware of it. However I can't seem to
> unmirror them to work on the problem, since they're in use, not that I'm
> good with grub anyway. -- I must be missing something obvious.

I haven't tested it, but I would try:

# grub-install /dev/sdb

Disclaimer:  I meant it - I haven't tried it, and if you break your
system, you get to keep both pieces...

-- 
Ed Wilts, RHCE
Mounds View, MN, USA
mailto:ewilts ewilts org
Member #1, Red Hat Community Ambassador Program