CentOS - Aug 2005 - RAID5 - MBR and default grub config on CentOS 4

greetings,

i just know i have read several times on this list and in other places that
on a RAID5 array that the MBR should be placed on the /boot partition.

is this truly correct and if so, why?

my experiences of putting the MBR on the /boot partition are contrary to
that it will even work and boot that way...

comments please?

regards,

 - rh

--
Robert Hanson
Abba Communications
http://www.abbacomm.net

On Mon, 2005-08-29 at 10:20 -0700, Robert Hanson wrote:
> greetings,
> 
> i just know i have read several times on this list and in other places that
> on a RAID5 array that the MBR should be placed on the /boot partition.
> 
> is this truly correct and if so, why?
> 
> my experiences of putting the MBR on the /boot partition are contrary to
> that it will even work and boot that way...
> 
> comments please?
----
You don't say whether this is hardware or software raid.

mbr should be put in boot blocks unless you have some other boot manager
handling boot and needs to hand off the boot.

Craig

Robert Hanson <roberth at abbacomm.net> wrote:
> greetings, 
> i just know i have read several times on this list and in
> other places that on a RAID5 array that the MBR should be
> placed on the /boot partition.
Let's clarify that is a software RAID-5 (via MD).

And I don't think people mean the master boot record (MBR),
which can only go in cylinder 0 of the hard drive -- before
any disk slicing.

They mean you should make a separate /boot filesystem where
the kernel and initrd go.
> is this truly correct and if so, why?
Because kernel and any initrd (which contain the software
RAID support) must be loadable by the 16-bit Int13h Services.

If the /boot directory is in a filesystem that is a
software/OS stripe set (such as RAID-3/4/5/6/etc...), then
16-bit Int13h Services can't read it.
> my experiences of putting the MBR on the /boot partition
> are contrary to that it will even work and boot that way...
Correct.  I think they are referring to the kernel/initrd
files in a separate /boot filesystem that is not software
RAID (or only RAID-1/mirror).



-- 
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