[CentOS] Problem with dual-booting soft-RAID

[Feizhou]

> One thing that I think you may be missing is this ...
> 
> In grub ... hd0 is the first found hard drive ... hd1 is the second
> found hard drive, etc.
> 
> IF ... you remove the primary hard drive (ie power it off, and unplug
> the cable) ... then the drive that is left (that used to be hd1) is now
> hd0
> 
> So ... when booting, it will be seen as hd0 and you won't have an hd1.
> 
> Well ... at least that is what I have experienced in the past ... maybe
> someone else who is smarter than me would care to comment / verify this
> behavior.

I won't say that I am smarter than Johnny but I will verify that this is 
the behaviour of grub and is so documented.

"Note that GRUB does not distinguish IDE from SCSI - it simply counts 
the drive numbers from zero, regardless of their type. Normally, any IDE 
drive number is less than any SCSI drive number, although that is not 
true if you change the boot sequence by swapping IDE and SCSI drives in 
your BIOS."

found at 
http://www.gnu.org/software/grub/manual/html_node/Naming-convention.html

So having the default menu item load from the first disk works in this case.