Re: RAID Questions

[Miles Fidelman <mfidelman@meetinghouse.net>]

Tom H wrote:
> On Tue, Jul 6, 2010 at 8:15 PM, Miles Fidelman
> <mfidelman@meetinghouse.net>  wrote:
>
>    
> > shell>  grub-install hd0
> > shell>  grub-install hd1
> >      
> With these grub-install invocations, you will not be able to boot in
> degraded mode.
>
> You have to set both sda and sdb to hd0 but you cannot do that in
> device.map. You have to use the grub shell:
>    
I'm pretty sure you're wrong on this - at least it's worked for me in 
the past.

You DON'T have to set both sda and sdb to hd0 - what you have to achieve is:

1. have identical bits in /boot on both drives - so that they can be 
read before the raid array gets created
-- if you've built with RAID-1, and done a standard install, this 
happens automatically

2. get grub installed on the MBR of both drives - so your BIOS can boot 
off either drive
-- grub-install does this for you

3. set up your BIOS to fallback to sdb if sda fails to respond

4. set up your menu.1st to boot off sdb if sda fails to respond

I'm pretty sure that things will break badly if grub things that both 
disks are hd0.

Miles Fidelman

--
In theory, there is no difference between theory and practice.
In<fnord>  practice, there is.   .... Yogi Berra