[CentOS] Raid Cards

Fri Jun 9 15:22:15 UTC 2006
William L. Maltby <BillsCentOS at triad.rr.com>

On Fri, 2006-06-09 at 10:10 -0500, Les Mikesell wrote:
> On Fri, 2006-06-09 at 22:58 +0800, Feizhou wrote:
> > > I just looked at the boot sector on the 3 machines that I have running 
> > > software raid1.  It looks like the installer got it right on all 3.  
> > > IIRC, one was installed as CentOS 4.1, another as 4.2, and another as 4.3.
> > 
> > The installer will install grub. Just not properly. If the first disk 
> > dies, when the box comes up, the previous second disk grub stage 1 will 
> > load but it will not look for the stage 2 on the current disk and 
> > therefore fail.
> 
> That will depend on what your bios does when the first drive fails and
> whether you've had to move it to make it boot at all.  On the scsi
> systems where I've used it, the 2nd drive will boot and everything
> on the cable shifts up if the first drive fails or is removed.
> IDE systems are different - and normally won't boot if a failed drive
> is still connected.

If the BIOS is able to get around the failed drive, HD device IDs are
shifted: 0x81->0x80, 0x82->0x82, ... Ditto if you tell BIOS to boot from
D:, E:, ... and IDs "wrap" if needed: 0x83->0x80, 0x80->0x81...

And if from other device(s), somewhat similar, but different,
adjustments *may* occur, e.g. El Torito Spec Boot CD (Phoenix Bios/IBM
circa 1995?).


-- 
Bill
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