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geoffrey
Asked: 2012-10-01 05:23:31 +0800 CST

"Swap not available" - I must manually "swapon" after every reboot

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I am on Ubuntu 12.04, Thinkpad Edge 13, encrypted home. A message in the System Monitor tells me that swap is "not available". I can get it back using the swapon option in gparted (I thought I could also do sudo swapon -a in a terminal, but that does not work). The problem is that I have to swapon after every reboot. How can I switch it back on so it stays on even after a reboot?

my fstab:

# # <file system> <mount point> <type> <options> <dump> <pass> 
proc /proc proc nodev,noexec,nosuid 0 0 
# / was on /dev/sda5 during installation 
UUID=47641b93-9d12-4e6a-b803-dde28f0e5725 / ext4 errors=remount-ro 0 1
swap

2 Answers

  1. Best Answer

    You have no configuration for swap in /etc/fstab. Add following line to that file:

    UUID=<uuid> none   swap    sw    0       0

    You have to replace <uuid> with the uuid of your swap partition. To do that, run sudo blkid

    $ sudo blkid
/dev/sda1: LABEL="System Reserved" UUID="88A0D0A1A0D09752" TYPE="ntfs" 
/dev/sda2: UUID="0620D9F920D9EFA3" TYPE="ntfs" 
/dev/sda5: UUID="c282b418-2045-4852-8789-88a44360a0bb" TYPE="ext4" 
/dev/sda6: UUID="f99c6a0c-790a-45ca-a1a9-8874f5a2999b" TYPE="ext4" 
/dev/sda7: UUID="4cc2e909-ebd1-4c72-abee-aa32035bf330" TYPE="swap"

    This is a list of my partitions, and as you see, /dev/sda7 is my swap partition. So you can copy the value of UUID corresponding to your swap, omitting the quotes, and use it for your fstab file.

    • 27

  2. After the upgrade to 12.04, certain little anomalies occurred. I was unaware my swap partition wasn't working until I tried to open a large file in Gimp.

    blkid shows:

    /dev/sdb6: UUID="3e0550cf-4a55-4aa8-80fa-24103c1b25a7" TYPE="swap"

    but it is not active according to System Monitor. The UUID was definitely right but no go ... not sure how I got to this command:

    blkid -p /dev/mapper/foo-swap_1
error: /dev/mapper/foo-swap_1: No such file or directory

    File manager showed me a 0 byte icon, filename control, -- so what was supposed to be written there? By what?

    sudo swapon --all --verbose yielded
swapon: cannot find the device for UUID=3e0550cf-4a55-4aa80fa-24103c1b25a7

    I edited the /etc/fstab file adding

    /dev/sdb6   none    swap    sw  0   0

    Reboot and System Monitor shows it active.

    This was the first site I found for help; in my case, the UUID did not work even though it was in fstab, so there is something missing 'in the middle'. This may help someone, who knows.

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