System Resource Usage

When your server runs out of memory, one of two things generally happens:

  • The out of memory killer comes along and kills processes.
  • Your system uses swap as a form of slower memory.

Swap is simply putting pages of memory from your RAM into a file / partition to increase the capacity of it.

You can find the amount of swap you have free by running:

free -h

To change it, you need to disable your existing swap and resize it:

# change this to where you wish your swapfile to be stored
SWAPFILE=/swapfile

sudo swapoff -a
# we generate a swapfile of size bs * count, in this case 8GB.
sudo dd if=/dev/zero of=$SWAPFILE bs=1G count=8
sudo chmod 0600 $SWAPFILE
sudo mkswap $SWAPFILE
sudo swapon $SWAPFILE

Then check to make sure your amount of swap has changed:

free -h