root won't mount by UUID, device doesn't exist

[Alex Mauer]

My system won't boot using the UUID= syntax, because the root partition doesn't get a /dev/disk/by-uuid link. All the other partitions do:

/dev/disk/by-uuid$ ls -l
total 0
lrwxrwxrwx 1 root root 10 2007-10-01 17:45 00000000433B49BF -> ../../sda1
lrwxrwxrwx 1 root root 10 2007-10-01 17:45 32B88978B8893B7D -> ../../sda4
lrwxrwxrwx 1 root root 10 2007-10-01 23:20 8C3D-06FF -> ../../sdb1
lrwxrwxrwx 1 root root 10 2007-10-01 17:45 9f88936b-5275-4df5-916c-3ac71563ec59 -> ../../sda2
lrwxrwxrwx 1 root root 10 2007-10-01 17:45 a2e4735b-f48b-49d8-8937-3e01da5ea0e9 -> ../../sda7
lrwxrwxrwx 1 root root 10 2007-10-01 17:45 dbd1c76b-6911-46ef-bd3c-aa03755462da -> ../../sda5

It does have a UUID though:

$ sudo dumpe2fs /dev/sda6 | head -n 3
dumpe2fs 1.40.2 (12-Jul-2007)
Filesystem volume name: /
Last mounted on: <not available>
Filesystem UUID: 2b41b6d0-b2d9-4296-9be7-e2928828eaf0

booting with root=/dev/sda6 works fine.

[Adam Niedling (krychek)]

Has this problem been solved already?

[Alex Mauer (hawke)]

No, this has not been solved.

[Craig Maloney (craig-decafbad)]

Please provide more information about this bug,such as the version of Ubuntu you are using, and what kernel version you are using. Also, have you had this issue with Hardy Heron?

[Alex Mauer (hawke)]

Hardy Heron, kernel 2.6.24-20-generic is the one I'm currently using. All previous kernels have had the same problem.

[Alex Mauer (hawke)]

2.6.27-1 also has this problem.

[Alex Mauer (hawke)]

Changing status to prevent expiration

[Waleed Hamra (w-hamra1987)]

Alex, try the following command in a terminal and see if it helps

sudo ln /dev/sda6 /dev/disk/by-uuid/$(sudo vol_id --uuid /dev/sda6) -s

this will create a uuid entry for your /dev/sda6 which you say is your root partition

[Alex Mauer (hawke)]

While I would assume that manually symlinking it would work, shouldn't the system do this sort of thing automatically? Isn't that the point of the whole UUID thing? I mean, I can obviously work around it by just setting my root device to /dev/sda6 in fstab and grub, so merely getting it working isn't exactly the problem.

[Scott James Remnant (Canonical) (canonical-scott)]

Please provide the output of "vol_id /dev/sda6"

[Alex Mauer (hawke)]

(It's /dev/sda5 now after some Partition Magic use)

$ vol_id /dev/sda5
ID_FS_USAGE=raid
ID_FS_TYPE=LVM2_member
ID_FS_VERSION=LVM2 001
ID_FS_UUID=ZtGwOc-0MgW-no0B-Ic6F-eWz0-txui-YmjS49
ID_FS_UUID_ENC=ZtGwOc-0MgW-no0B-Ic6F-eWz0-txui-YmjS49
ID_FS_LABEL=
ID_FS_LABEL_ENC=
ID_FS_LABEL_SAFE=

[Scott James Remnant (Canonical) (canonical-scott)]

This is an LVM Physical Volume

What does "lvm pvs" output? How about "lvm vgs" and "lvm lvs" ?

[Alex Mauer (hawke)]

lvm2 isn't installed. After installing it:

$ sudo lvm pvs
  PV VG Fmt Attr PSize PFree
  /dev/sda5 lvm2 -- 14.65G 14.65G
$ sudo lvm lvs

I don't know of any reason that that device would be an LVM PV.

[Alex Mauer (hawke)]

Information provided.

[Scott James Remnant (Canonical) (canonical-scott)]

Have you used LVM in the past on this disk? When you formatted it did you wipe the disk first?

[Alex Mauer (hawke)]

I don't believe I've ever used LVM on this partition. It's possible that I abortively attempted to use LVM on it when the system was installed, which would have been around Dapper Drake or earlier.

[Scott James Remnant (Canonical) (canonical-scott)]

Well, the meta-data is there and that's what's confusing things. This is only not removed by manual partitioning software.