transplamting RAID-1 drives

[Paul Johnson]

On 10/17/07, Jack Howarth <howarth at bromo.msbb.uc.edu> wrote:
>    I ran into an interesting problem which I wonder if
> anyone has some insights into. The motherboard on a
> i386 Fedora 7 workstation died recently and we hoped that
> the existing SATA RAID-1 mirror could be moved into a
> new workstation using an opteron processor. The machine
> could find the MBR to start the boot process but couldn't
> find the md partitions to complete the boot. Interestingly
> booting i386 Fedora 7 in linux rescue mode presented no
> problem in mounting the same md partitions. The only
> difference I noticed was that the new motherboards BIOS
> showed a channel 0 with the IDE devices (DVD+/-RW) and
> a channel 2 and 3 with the two SATA drives. However under
> the linux rescue mode the two SATA drives appeared to be
> mounted the same (as sda and sdb). I am rather puzzled
> as to what aspect of the RAID-1 configuration could be
> causing the transplant of the RAID-1 mirror to fail.
>          Jack
> ps I eventually transfered the data off the drive and
> started with two new SATA drives with x86_64 Fedora 7
> although I realize I probably could have chrooted the
> sysimage under i386 Fedora 7 and reinstalled grub
> on the MBR.
>
> --

I've noticed this before in a dell workstation. The Bios controls the
order in which the disk subsystems are found. Ie, does it have
internal sata, internal hd, and external usb in a certain order.  I
can change that.  But when I boot off the cd rom, it ignores that bios
ordering, and finds devices as it wants to.  To stop it from calling
the internal ide drive /dev/sda, I had to use the bios to make it read
the sata drives first as /dev/sda and /dev/sdb, and the ide device
gets pushed to the end of the alphabet.  using the scsi drivers for
all devices (ide and sata) is not a very good system when a computer
has both sata and ide devices.  most systems don't have both, so most
users don't encounter it/


-- 
Paul E. Johnson
Professor, Political Science
1541 Lilac Lane, Room 504
University of Kansas