How to find the swap uuid

Question

I am in the process of setting up a raid. sda was used during the installation and I just copied the partition table of sda to sdb like so:

$ sudo sfdisk -dL /dev/sda > partition_table_sda
$ sudo sfdisk /dev/sdb < partition_table_sda

However I notice that sda has a uuid for the swapspace, but sdb does not:

$ sudo blkid
/dev/sda5: UUID="vvvvvvvv-wwww-xxxx-yyyy-zzzzzzzzzzzz" TYPE="swap" 
/dev/sda1: UUID="vvvvvvvv-wwww-xxxx-yyyy-zzzzzzzzzzzz" TYPE="ext4" 
/dev/sdb1: UUID="vvvvvvvv-wwww-xxxx-yyyy-zzzzzzzzzzzz" TYPE="ext4"

The partition looks correct though, it's just the uuid that is missing:

$ sudo fdisk -l

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0xzzzzzzzz

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048   960002047   480000000   83  Linux
/dev/sda2       960004094   976771071     8383489    5  Extended
Partition 2 does not start on physical sector boundary.
/dev/sda5       960004096   976771071     8383488   82  Linux swap / Solaris

Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0xzzzzzzzz

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *        2048   960002047   480000000   83  Linux
/dev/sdb2       960004094   976771071     8383489    5  Extended
Partition 2 does not start on physical sector boundary.
/dev/sdb5       960004096   976771071     8383488   82  Linux swap / Solaris

So how can I assign a uuid to the swapspace sdb5? Or if it already has a uuid, how can I print it out?

Solution

Have you formatted the swap partition? Once you part your disk and reserve a partition for swap you have to:

sudo mkswap /dev/sdb5

after that your swap's UUID should be displayed when entering blkid command.

Comments

[mulllhausen]

ah i didn't realize that. i will give it a go tomorrow

[QkiZ]

blkid doesn't return UUID for swap. Only regular volumes.