Finding The Uuid For A File System Device; Using Uuids In The Boot Loader And /Etc/Fstab File (X86) - Novell LINUX ENTERPRISE SERVER 10 - STORAGE ADMINISTRATION GUIDE 7-2007 Administration Manual

during the install, it might be assigned to /dev/sdg1 after the SAN is connected. One way to
avoid this problem is to use the UUID in the boot loader and /etc/fstab files for the boot
device.
A UUID never changes, no matter where the device is mounted, so it can always be found at boot. In
a boot loader file, you typically specify the location of the device (such as /dev/sda1 or /dev/
evms/sda1) to mount it at system boot. The boot loader can also mount devices by their UUIDs
and administrator-specified volume labels. However, if you use a label and file location, you cannot
change the label name when the partition is mounted.
You can use the UUID as criterion for assembling and activating software RAID devices. When a
RAID is created, the md driver generates a UUID for the device, and stores the value in the md
superblock.

3.2.2 Finding the UUID for a File System Device

You can find the UUID for any block device in the /dev/disk/by-uuid directory. For example,
a UUID looks like this:
e014e482-1c2d-4d09-84ec-61b3aefde77a
3.3 Using UUIDs in the Boot Loader and /etc/
fstab File (x86)
After the install, you can optionally use the following procedure to configure the UUID for the
system device in the boot loader and /etc/fstab files for your x86 system.
1 Install the SUSE
2 After the install, boot the system.
3 Open a terminal console as the root user or equivalent.
4 Navigate to the /dev/disk/by-uuid directory to find the UUID for the device where you
5 Edit /boot/grub/menu.1st file, using the Boot Loader option in YaST2 or using a text
32 SLES 10 Storage Administration Guide
®
Linux Enterprise Server for x86 with no SAN devices connected.
installed /boot, /root, and swap.
4a At the terminal console prompt, enter
cd /dev/disk/by-uuid
4b List all partitions by entering
ll
4c Find the UUID, such as
e014e482-1c2d-4d09-84ec-61b3aefde77a —> /dev/sda1
editor.
For example, change
kernel /boot/vmlinuz root=/dev/sda1
to
kernel /boot/vmlinuz root=/dev/disk/by-uuid/e014e482-1c2d-4d09-
84ec-61b3aefde77a
IMPORTANT: Make a copy of the original boot entry, then modify the copy. If you make a
mistake, you can boot the server without the SAN connected, and fix the error.