Swap

Swap

If running out of swap you can add 257MB more. First have a look at what you have available:

  # free
               total       used       free     shared    buffers     cached
  Mem:        256216     252208       4008     118100      56996      46944
  -/+ buffers/cache:     148268     107948
  Swap:       224900      51268     173632

Next create a file without holes and a multiple of 4K in size:

  # dd if=/dev/zero of=/extra-swap bs=1024 count=262144
  262144+0 records in
  262144+0 records out

Now mark it as a swap file by writing a signature to its beginning which contains some administrative information and is used by the kernel:

  # mkswap /extra-swap 
  Setting up swapspace version 1, size = 268431360 bytes

Now tell the kernel about the new swap file:

  # swapon /extra-swap

Now check it is there!

  # free
               total       used       free     shared    buffers     cached
  Mem:        256216     252448       3768     118100      56996      46944
  -/+ buffers/cache:     148508     107708
  Swap:       487036      51268     435768

To remove the swap file from usage:

  # swapoff /extra-swap

You can add to /etc/fstab:

  /extra-swap        none        swap        sw     0     0

Then on boot when swapon -a is run the new swap will be added to swap space.