Swap Space Not Activated On Boot

[Nils Kassube]

Graham Watkins wrote:
> I've recently become aware that the 4Gb swap partition I created
> during the installation process is not being started on boot.
> Initially at least, this was due to my own stupidity because I
> somehow forgot to format it.  I have since formatted it using
> gnome-disks but it is still not available on boot although I can
> start it manually in gnome-disks.

> I think I probably need to change something in fstab but so far all my
> tinkering has been in vain.

> sudo fdisk -l
> 
> Disk /dev/sda: 320.1 GB, 320072933376 bytes
[...]
>     Device Boot      Start         End      Blocks   Id  System
> /dev/sda1   *          63   625141759   312570848+  83  Linux
> 
> Disk /dev/sdb: 160.0 GB, 160041885696 bytes
[...]
>     Device Boot      Start         End      Blocks   Id  System
> /dev/sdb1   *        2048   117270527    58634240   83  Linux
> /dev/sdb2       117272574   312580095    97653761    5  Extended
> /dev/sdb5       117272576   125270015     3998720   82  Linux swap /
> Solaris
> /dev/sdb6       125272064   312580095    93654016   83  Linux
> 
> sudo cat /etc/fstab
[...]
> # / was on /dev/sdb1 during installation
> UUID=ac228376-2087-45ee-a47e-6018398186e2 /               ext4
> errors=remount-ro 0       1
> # /home was on /dev/sdb6 during installation
> UUID=fba7b900-46aa-402d-88a2-359f05945a2f /home           ext4
> defaults 0       2
> # swap was on /dev/sdb5 during installation
> UUID=83ffea71-702b-4570-9c9a-3680f3290c56 none            swap    sw

You wrote that you formatted the swap partition but probably you didn't 
change the UUID of the fstab entry. You can find out the UUID with the 
command

ls -l /dev/disk/by-uuid/ | grep sdb5

and then change the string after the "UUID=" of the fstab entry 
according to the output of the command above.

After modifying the fstab you can use the commands

sudo swapon -a
free -h

to check if the change was successful.

Nils