Swap Space | skybert.net

Swap Space

Getting the Size Right

I've heard and read many arguments over the years about the correct amount of swap space on Linux. The requirement and reality has changed a lot for swap over time and this article is the best I've read summarising it all in a convincing manner.

The short conclusion from this article is:

swap = 2GB;

if (ram <= 1GB) {
  swap = ram;
else if (ram < 4GB) {
  swap = ram / 2;

Adding a Swap File

I love the simplicity with which you can add and remove swap files in runtime. This is how I added a 1GB swap file, adding an entry for it to/etc/fstab and activating it:

# dd if=/dev/zero of=/var/lib/swap.file bs=1024 count=1024000
# mkswap /var/lib/swap.file
# echo "/var/lib/swap.file swap swap defaults 0 0" >> /etc/fstab
# chmod 0600 /var/lib/swap.file
# swapon -a

That's it. Runningfree -m shows that I now have 1GB swap available. There's no greatness where there's no simplicity. And Linux is full of such simplicity :-)

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