Device IDs Change On Boot

jmoschetti45 · 01-03-2010, 03:38 PM

I have 2 internal SCSI drives in the box.
I also have an external USB HDD that's almost always there, so it's in fstab to be mounted somewhere.

When I boot with the external connected, here's what I get:
External = sda
Internal SCSI-1 = sdb
Internal SCSI-2 = sdc

Without it:
Internal SCSI-1 = sda
Internal SCSI-2 = sdb

How do I fix this? The SCSI drive's are a RAID setup, so if I boot without the external I have complete RAID failure.

paulsm4 · 01-03-2010, 03:47 PM

Maybe you can hard code the disk order in your BIOS.

Otherwise, you'll probably just have to:

a) configure your RAID to use sda and sdb as SCSI-1 and SCSI-2
b) get in the habit of inserting your external drive *after* you boot your PC.

jmoschetti45 · 01-03-2010, 04:13 PM

Nothing in the BIOS along those lines.

Problem is, the external is almost always here, and I'm not, so it's there on boot. Issue is, power here is unreliable at best and it ends up rebooting a lot, so I don't have the option of not plugging it in until it's booted.

Usually I just unmount/unplug it while the box is on when on the rare occasion I do take it with me. Problem then is when it reboots next, I have no RAID.

I'm thinking there's not going to be an easy solution to this...

phil.d.g · 01-03-2010, 04:42 PM

Can you post some more details? Specifically what RAID system are you using?

If your using mdadm can you post the contents of /etc/mdadm/mdadm.conf?

The order in which drives are labelled isn't guaranteed, and there is a lot of support for identifying specific drives/partitions without relying on the /dev/sdXY reference.