UUIDs for partitions in Ubuntu Edgy Eft 6.10

14.02.2007 at 17:04

I recently updated a Ubuntu Dapper Drake (6.06) system to Edgy Eft (6.10). Other than i had to reinstall/reconfigure my xserver everything went ok. However by the next reboot i noticed a strange root=[long alphanumeric value] kernel parameter in my grub prompt. After some investigation i found out that my /etc/fstab contained the same strange ids.

# /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults        0       0
# /dev/hdc5 -- converted during upgrade to edgy
UUID=048b4608-5241-4dc4-8671-f8290cb55af5 / ext3 defaults,errors=remount-ro 0 1
# /dev/hdc1 -- converted during upgrade to edgy
UUID=05c63290-f5b8-4afb-97c1-fb7e15ad6ed8 /boot ext2 defaults 0 2
# /dev/hdc10 -- converted during upgrade to edgy
UUID=06ee7e3e-768b-4a51-a31f-0e70ec314e81 /data ext3 defaults 0 2
# /dev/hdc7 -- converted during upgrade to edgy
UUID=56ef33df-9f30-4577-b1de-83b540fd3519 /home ext3 defaults 0 2
# /dev/hdc11 -- converted during upgrade to edgy
UUID=9628b57a-cd57-4ffb-a0e7-6d2bc349e46b /media/hdc11 ext3 defaults 0 2
# /dev/hdc12 -- converted during upgrade to edgy
UUID=caa74b76-416b-46aa-8c0a-f6348f6afbcd /media/hdc12 ext3 defaults 0 2
# /dev/hdc13 -- converted during upgrade to edgy
UUID=fe873ec7-3176-4aad-b0b1-9164f938f213 /media/hdc13 ext3 defaults 0 2
# /dev/hdd1 -- converted during upgrade to edgy
UUID=9E745EF6745ED11F /media/hdd1 ntfs defaults,nls=utf8,umask=007,gid=46 0 1
# /dev/hdd5 -- converted during upgrade to edgy
UUID=78DB-0025 /media/hdd5 vfat defaults,utf8,umask=007,gid=46 0 1
# /dev/hdc9 -- converted during upgrade to edgy
UUID=b43c2193-3c00-48d0-8c29-c2fa7212c457 /usr ext3 defaults 0 2
# /dev/hdc8 -- converted during upgrade to edgy
UUID=7cec1fb3-c2f2-46dc-9782-7228d57b9f2b /var ext3 defaults 0 2
# /dev/hdc6 -- converted during upgrade to edgy
UUID=6996378e-a37b-49b8-8e91-65164bef7626 none swap sw 0 0
/dev/hda        /media/cdrom0   udf,iso9660 user,noauto     0       0
/dev/fd0        /media/floppy0  auto    rw,user,noauto  0       0

My first thought: what a mess! Luckily they left some commends in there.

So what is the purpose of those numbers which are not so human friendly? They should uniquely identify a given partition. Which means you could swap your disks/memorykeys/whatever and the system will still mount the correct partition on the right place. Another thing this mechanism tries to work around is, that the device names depend on module load order. With the development in recent kernels which try to scan the hardware and detect devices in parallel, to speed up boot time, it will be entirely random which devices turns up as /dev/sda.

Listing UUIDs

You may ask how can i check the mappings between UUIDs and devices? Good question -- there are a few different ways, /sbin/blkid will happily print a list of device names, filesystem labels and UUIDs for you even if you aren't root. While sudo vol_id -u <partion> will give you only the exact UUID for the requested partiton.

After i have informed myself about those UUIDs i am no longer that scared but i still think this is a suboptimal solution they are just way too human unfriendly. A solution based on diks LABELS is probably the better approach.

Marc

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