Multiple device (in raid) persistant naming - best practices?

[Simen Thoresen <simentt@dolphinics.no>]

Hi all,

I'm trying to wrap my mind around how to figure out which of several (in a 
raid set) disks is which physical disk.

How is this done these days?

My constraints;
-My filesystem is on /dev/mdX, so I cannot easily assign a label to a single 
disk without playing with micro-partitions on the disks
-My BIOS/kernel/controllers play reordering games on me. I'm pretty sure the 
disks have moved around, and my boot-disks that started out as /dev/sda and 
/dev/sdb (ports 0 and 1 on my NForce4 SATA-controller) are now sdc and sdd. 
I think both kernel-updates and BIOS-updates may have changed the order, but 
I'm not sure about either.
-My disks do not display activity thru leds, nor are they noisy enough that 
a dd from any one of them will be discernible over the rest of them.
-I did not note down which serial-numbers are attached to which disk, altho 
I know hdparm -I reports them. I was not able to coax serial-numbers from 
udevinfo.

I'm running an RHEL4-based system (2.6.9 with a truckload of vendor 
patches), but I'm wondering if there are any neat udev-hacks or similar that 
make matching /dev/sdX -devics with the drives possible.

Thank you for all replies.

Yours,
-S
-- 
Simen Thoresen, Dolphin ICS