UsingUUID

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Since Edgy, Ubuntu requires the use of '''UUID''' or '''LABEL''' (for filesystems including swap), or udev-created symlinks (for removable media like CDROMs and USB drives). Directly using {{{/dev/hd*}}} or {{{/dev/sd*}}} is no longer supported (since these device assignments can change from boot to boot):

 * all filesystems should be specified by {{{UUID=}}} or {{{LABEL=}}}
 * all physical devices should be specified by a symlink (e.g. {{{/dev/cdrom}}}, {{{/dev/disk/by-id/...}}}, etc.)

The files for which this is most critical are:
 * {{{/boot/grub/menu.lst}}}
 * {{{/etc/fstab}}}
 * {{{/etc/initramfs-tools/conf.d/resume}}}

=== Finding ===

UUIDs can be determined using the {{{vol_id}}} command. For example, to find the UUID for the filesystem on {{{/dev/sda1}}}:

{{{
$ sudo /sbin/vol_id -u /dev/sda1
79415992-7093-4a0e-a2e5-4574ed702d05
}}}

Symlinks created by udev can be found by searching for the target device in {{{/dev}}}. For example, to find {{{/dev/sda1}}}:

{{{
$ ls -la /dev/disk/by-id | grep /sda1$
lrwxrwxrwx 1 root root 10 8207-06-10 02:46 ata-ST2250823AS_3ND277BL-part1 -> ../../sda1
lrwxrwxrwx 1 root root 10 8207-06-10 02:46 scsi-1ATA_ST2250823AS_3ND277BL-part1 -> ../../sda1
}}}

=== Converting ===

To perform these UUID lookups and corrections automatically (which should have already happened during the Dapper to Edgy upgrade) please use:

 * For {{{/boot/grub/menu.lst}}}:
  {{{
sudo /usr/sbin/update-grub
}}}
 * For {{{/etc/fstab}}}:
  {{{
sudo rm -f /etc/fstab.pre-uuid
sudo /var/lib/dpkg/info/volumeid.postinst configure
}}}
 * For {{{/etc/initramfs-tools/conf.d/resume}}}, there is no automatic procedure:
  * Verify that {{{RESUME=}}} matches your {{{swap}}} line in {{{/etc/fstab}}}
  * After any adjustment, run {{{sudo update-initramfs -u}}}		 #REFRESH 0 http://help.ubuntu.com/community/UsingUUID

UsingUUID (last edited 2008-08-06 16:59:35 by localhost)