Tag Archives: swap

Create and mount SWAP file

In the Cloud era, virtual servers come with no swap. And it’s perfectly fine, cause swapping isn’t good in terms of performace, and Cloud technology is designed for horizontal scaling, so, if you need more memory, add another server.

However, it could be handy sometimes to have a some more room for testing (and save some money).

So here below one quick script to automatically create a 4GB swap file, activate and also tune some system parameters to limit the use of the swap only when really necessary:

fallocate -l 4G /swapfile
chmod 600 /swapfile
mkswap /swapfile
swapon /swapfile
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab
sysctl vm.swappiness=0
echo 'vm.swappiness=0' >> /etc/sysctl.conf
tail /etc/sysctl.conf

Swappiness: setting to zero means that the swap won’t be used unless absolutely necessary (you run out of memory), while a swappiness setting of 100 means that programs will be swapped to disk almost instantly.