Amazon Linux 2022 Tempfs
Things to know when migrating from Amazon Linux 1 or Amazon Linux 2 to Amazon Linux 2022 - tempfs
Amazon Linux 2022 comes equipped with /tmp directory mounted in memory. It’s visible in
df as a separate device
/dev/xvda1 8.0G 4.2G 3.9G 52% / tmpfs 986M 0 986M 0% /tmp
Rather than a fixed entry in /etc/fstab, it uses a service to remount the /tmp after a reboot
Tempfs is fast. Absurdly fast for something that looks like ‘a storage’. The service definition mentioned above automatically allocates 50% of RAM as possible storage.
If your software depends on a large volume of temporary files, you have to carefully measure the performance - if you fill in the /tmp with your files, and the demand for RAM from application raises, system will start using swap and that will obviously have a massive impact on performance
How to disable it
As mentioned earlier, it’s mounted after each reboot via a service, so it is as simple as stopping the service and then disabling it.
sudo systemctl disable tmp.mount sudo systemctl stop tmp.mount
But now the /tmp is useless, so let’s recreate it.
sudo rm -rf /tmp sudo mkdir /tmp sudo chmod 1777 /tmp
df -h should show you no /tmp as a separate mountpoint.