Configure Swap Space on Linux

Swap space acts as overflow memory when your server's RAM is fully utilised. While not a substitute for adequate RAM, a swap file prevents out-of-memory (OOM) crashes on servers with limited memory.

Check Current Swap

$swapon --show
$free -h

If no swap is configured, swapon --show returns no output.

Create a Swap File

Create a 2 GB swap file (adjust size as needed):

$fallocate -l 2G /swapfile
$chmod 600 /swapfile
$mkswap /swapfile
$swapon /swapfile

Verify swap is active:

$swapon --show

NAME      TYPE  SIZE USED PRIO
/swapfile file    2G   0B   -2

Make Swap Permanent

Add the swap file to /etc/fstab so it persists across reboots:

$echo '/swapfile none swap sw 0 0' | tee -a /etc/fstab

Tune Swappiness

The vm.swappiness kernel parameter controls how aggressively the kernel uses swap (0–100). A value of 10 is recommended for servers:

$sysctl vm.swappiness=10
$echo 'vm.swappiness=10' | tee -a /etc/sysctl.conf

Recommended Swap Sizes

[!NOTE] NVMe SSD-backed servers have fast swap performance. However, excessive swap usage indicates your server needs more RAM — consider upgrading your plan if swap is consistently in use.