FC scsi reordering during boot process

["John Madden" <jmadden@xxxxxxxxxxx>]

It's been about a week, quite a frustrating issue, and with the lack of info on it
out there, I feel like I'm about the first person to have run into it and actually
bothered to find a fix for it.  Here goes:

The situation: machine hooked to FC SAN, PCI scan order causes /dev entries to
change as LUN's are added and removed, paths are available and not available, etc.
 So telling the kernel from the bootloader that root=/dev/sda1 doesn't cut it. 
Devfs fixed this by specifying absolute paths to the controllers themselves, like
/dev/scsi/host0/bus0/etc and udev supposedly fixes it by just remembering where to
point /dev/sda.

I've had the devfs way working for some time but I'm looking to move to udev as
devfs will eventually be dropped from the kernel.  Udev is userspace-only though,
which forces the use (I assume) of an initrd during boot, but Debian's default
initrd's don't provide support for udev (Debian 3.1 is devfs-based).  I run stock
kernel.org kernels without modules, so this really comes down to getting udev to
order things correctly as far as I can tell.

Has anyone gotten such a scenario to work?  Basically, that'd be a udev-based
initrd that will maintain the /dev/sda pointer to the machine's internal SCSI disk
despite it being the last device on the PCI chain.  My attempts to build a
suitable one have been fruitless.

(And yes, I'm aware that if I just loaded the module last, yada yada, and that I
could just update the pointer to look at the proper device as I add LUN's, etc. 
Neither of these are the "right" way of doing things.)

Thanks,
  John




-- 
John Madden
UNIX Systems Engineer
Ivy Tech Community College of Indiana
jmadden@xxxxxxxxxxx
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