Setting up a loopback swap file is something I do fairly commonly on my virtual servers - RAM costs extra money - whereas SSD storage is common and included! Repartitioning’s too much messing around on DigitalOcean, so I set up a loopback file and it just works.
Here’s the commands to make a 2GB file (change count for different sizes):
yaleman@server:~# sudo dd if=/dev/zero of=/swap.img bs=1024 count=2097152
2097152+0 records in
2097152+0 records out
2147483648 bytes (2.1 GB) copied, 9.69851 s, 221 MB/s
yaleman@server:~# sudo chmod 0600 /swap.img
yaleman@server:~# sudo mkswap /swap.img
Setting up swapspace version 1, size = 2097148 KiB
no label, UUID=a78f6315-aba5-4d88-bb67-211f1a0c5e56
Edit the filesystem table:
yaleman@server:~# sudo vi /etc/fstab
Add the following line:
/swap.img none swap sw 0 1
Enable the swap now!
yaleman@server:~# sudo swapon /swap.img
Check what swap’s enabled:
yaleman@server:~# cat /proc/swaps .
Filename Type Size Used Priority
/swap.img file 2097148 52 -1
There ’tis!