Booting order / SATA onboard / IDE card

[Lennart Sorensen]

On Fri, May 14, 2010 at 08:14:56AM -0400, Alex Beamish wrote:
> My current home NFS server is failing, and I'm working on replacing it
> with a new machine, but I'm concerned about the disk boot order on the
> new machine.
> 
> The original NFS server has IDE drives, with the OS on the smaller,
> original drive (primary master) and the two data disks on the primary
> slave and secondary slave (it made sense to me to have the two data
> drives on separate channels). My motivation to change is that the
> secondary channel has been dead on this machine for some time. I can
> still get at the files, but I'd like to get things working properly
> again.
> 
> The intended replacement is a P4 3GHz Dell machine which has a single
> 80G SATA drive. I was planning on buying two 500G or 1T SATA drives as
> the data disks (RAID 1, mirrored), and installing an IDE card for a
> small, inexpensive system disk. However, now I'm wondering whether the
> BIOS on this new machine will be flexible enough to be able to boot
> off the IDE disk; I'm new to SATA drive machines. Anyway, that's plan
> A, and my preferred solution.
> 
> Plan B would be to leave the original SATA drive where it is in the
> new machine, use it as the system disk, and just move the original IDE
> data drives over to the new machine. The original NFS server is
> running openSolaris and the drives are using ZFS, in case anyone's
> curious.
> 
> Thoughts? Comments?

The order of drives at boot is up to the BIOS.  Now once linux loads
different issues occour.  The only sane thing to do in linux is to
use UUID (or LABEL) to refer to drives when mounting.  UUID is by far
preferable.  Most distributions do this by default on new installs these
days (at least I believe Fedora does it and I know Debian does).

The advantage of UUID (or LABEL) is that it doesn't matter what drive
is sda or sdc or whatever, you always refer to the right filesystem.

The only tricky bit is installing the bootloader on the correct disk.
udev might be able to take care of keeping the drive order consistent
as well.

-- 
Len Sorensen
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