[SOLVED] switch sd* with sd*

13stein.j · 06-08-2013, 08:13 PM

Is there any way I can switch sda(1,2,5) and sde(1,2). Not the data within them, but the letters a and e(permanently), I need this because my opensuse install was on sda but then it changed to sde and won't boot properly. Changing the letters in the dev folder was only temporary and worked for one session, after restart, it undid itself.

syg00 · 06-08-2013, 09:46 PM

Fix the problem, not the symptom.
Describe, in detail, what you mean by "won't boot properly". How did you change the /dev entries if it won't boot ?.

Have you checked the obvious places - fstab and boot config ?.

13stein.j · 06-08-2013, 09:56 PM

Quote:

Originally Posted by syg00

Fix the problem, not the symptom.
Describe, in detail, what you mean by "won't boot properly". How did you change the /dev entries if it won't boot ?.

My signature is the real deal, and when installing opensuse, sda and sde were mixed up, so now when I boot into sde, it boots to ubuntu, but a weird version of it. On the real ubuntu, I changed those entries, and it was temporary only.

Quote:

Originally Posted by syg00

Have you checked the obvious places - fstab and boot config ?.

I have tried to edit opensuse's fstab to go by sde instead of sda, and also by uuid, but, no luck.

syg00 · 06-08-2013, 10:08 PM

The BIOS determines the drive order at boot - but each Linux uses udev to assign the /dev/ nodes.
Is this a mix of one IDE and one ATA drive by any chance ?. I had all sorts of trouble with different distros using different names.

UUID should be the answer, especially with grub2.

From a Linux (even a liveCD) go here untar the download and run it - post the RESULTS.txt here.

David the H. · 06-09-2013, 08:35 AM

On most systems these days devices are created by udev.

http://www.reactivated.net/writing_udev_rules.html

You can write your own udev rules for creating devices if you want, but it's generally NOT recommended to try altering the default settings. It should be safe to additionally create your own personal symlinks to them, however. Indeed, your system should already have several preset symlinks set up for you in /dev/disk.

For fstab and related mount settings, however, you're better off just configuring them to use UUID, or perhaps LABEL, instead of the dev entry, as syg00 mentioned.

13stein.j · 06-09-2013, 09:06 PM

Quote:

Originally Posted by David the H.

On most systems these days devices are created by udev.

http://www.reactivated.net/writing_udev_rules.html

You can write your own udev rules for creating devices

This seems the most useful so check if what I have to add is wrong

Code:

KERNEL=="sda", NAME="sde"
KERNEL=="sda1", NAME="sde1"
KERNEL=="sda2", NAME="sde2"
KERNEL=="sda5", NAME="sde5"
KERNEL=="sde", NAME="sda"
KERNEL=="sde1", NAME="sda1"
KERNEL=="sde2", NAME="sda2"

And, where would I write these rules?

jlinkels · 06-09-2013, 09:18 PM

A question to all who have more experience than I have.

Changing drive letters with udev is nice and fine, but most Linux systems use initrd. So rewriting udev rules does not change the drive letters during boot. Only afterwards if the system has booted, and then the udev rules are carried out according to the /etc/udev settings. But it seems to me that that is too late.

I agree that using UUIDs in grub.conf is the correct way to go.

jlinkels

13stein.j · 06-09-2013, 09:25 PM

Quote:

Originally Posted by jlinkels

A question to all who have more experience than I have.

Changing drive letters with udev is nice and fine, but most Linux systems use initrd. So rewriting udev rules does not change the drive letters during boot. Only afterwards if the system has booted, and then the udev rules are carried out according to the /etc/udev settings. But it seems to me that that is too late.

I agree that using UUIDs in grub.conf is the correct way to go.

jlinkels

Grub's configuration is not the problem, I have already tried using uuid, but, I will try the udev rules, post if it did not work, and then ask how to do the same with initrd.

13stein.j · 06-10-2013, 06:56 PM

Quote:

Originally Posted by 13stein.j

This seems the most useful so check if what I have to add is wrong

Code:

KERNEL=="sda", NAME="sde"
KERNEL=="sda1", NAME="sde1"
KERNEL=="sda2", NAME="sde2"
KERNEL=="sda5", NAME="sde5"
KERNEL=="sde", NAME="sda"
KERNEL=="sde1", NAME="sda1"
KERNEL=="sde2", NAME="sda2"

And, where would I write these rules?

These rules fixed everything! But, I had to make a few tweaks, 1, name this as 50-udev.rules, 2, do the same thing, but add DISPLAY:"0" at the end if each line and name it 10-local.rules, 3, copy these rules to each install except for OpenSuse, 4 start/restart udev, 5, update grub. Works like a charm, many thanks.