Archivo swap

How do I add more swap?

* Usually, people associate swap with a swap partition, maybe
because they've been proposed to create a swap partition on install.
In fact any file can be used as a swapping device, be it a partition
or a conventional file. If you're considering responsiveness, my
advice: add more RAM. Swapping to a partition or a file won't change
anything.
* We will add more swap by adding a swap file.

Adding more swap is a four-step process :
o a- Creating a file the size you want.
o b- Formatting that file to create a swapping device.
o c- Adding the swap to the running system.
o d- Making the change permanent.

We will consider (as an example) a 512 Mb swap need.

a- Creating a file the size you want :

We will create a /mnt/512Mb.swap swap file.

sudo dd if=/dev/zero of=/mnt/512Mb.swap bs=1M count=512

What is important here is count=512, which means we want our file to
contain 512 blocks of bs=1M, which means block size = 1 MegaBytes.
Be careful *not* to do this dd of=/mnt/512Mb.swap bs=1M seek=512 count=0
Though the file grows to 512Mb immediately,it will have holes that
makes it unusable.

b- Formatting that file to create a swapping device :

sudo mkswap /mnt/512Mb.swap

c- Adding the swap to the running system :

sudo swapon /mnt/512Mb.swap

You can see with "cat /proc/meminfo" that your additionnal swap is
now available.

d- Making the change permanent :

edit your /etc/fstab:

sudo gedit /etc/fstab

and add this line at the end of the file:

/mnt/512Mb.swap none swap sw 0 0

save and reboot

Fuente: https://help.ubuntu.com/community/SwapFaq