Ubuntu Slowdown – Dual Boot Loses Swap UUID [Fix]

December 16, 2009 by rich scadding 3 Comments

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ubuntu-logo-100x90This was reported as an issue before when dual-booting Ubuntu with another distro. Basically the Swap UUID Doesn’t get updated in /etc/fstab when another distro is installed on another partition.

I installed Fedora for a test run on a spare partition, with Grub being installed to MBR.

Later after an Ubuntu update, which included a new kernel and also a newer Grub, Ubuntu took back control of Grub.

I booted into Ubuntu, only to find that everything was a bit sluggish, and having experienced this before, I checked my Swap partition in  readiness to solve this problem which I had a feeling was repeating itself.

Check Swap:

free -m

With the result:

Swap:            0          0          0

Fix with “blkid” to find the real UUID of the Swap Partition:

blkid


/dev/sda1: LABEL="ACER" UUID="320D-180E" TYPE="vfat"
/dev/sda2: LABEL="Fedora-12-i686-L" UUID="3b915b51-c7ce-4077-975d-df2a177b94cb" TYPE="ext4"
/dev/sda3: UUID="78a42ee0-4d8a-474c-9cd6-b3f3a6dd6449" TYPE="ext4"
/dev/sda4: UUID="4bfbb29b-78da-4172-ae54-b1bb934de7f5" TYPE="swap"

Then use Nano to Fstab and change the old Swap UUID to the new UUID:

sudo nano /etc/fstab

Now just turn Swap on and check used memory again:

sudo swapon -a

with the result:

free -m

   Swap:         1153          0       1153

So there you have it, if you install another Linux distro on a spare partition to dual-boot and use the same Swap partition, you may find that when you boot into Ubuntu that it is a little sluggish than usual.

This is a known problem for dual and triple booters, but easily remedied, as you see above.

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