Configuring Swap on ZRAM
In Fedora 33 some editions enabled swap on ZRAM by default. Fedora CoreOS currently has the
zram-generator included but no configuration in place to enable swap on ZRAM by default. In order to configure swap on ZRAM you can lay down a configuration file via Ignition that will tell the zram generator to set up swap on top of a zram device.
The documentation for the config file format lives in the upstream documentation along with a comprehensive example. The most basic form of a configuration file that will set up a
zram0 device for swap is:
variant: fcos version: 1.4.0 passwd: users: - name: core ssh_authorized_keys: - $pubkey storage: files: - path: /etc/systemd/zram-generator.conf mode: 0644 contents: inline: | # This config file enables a /dev/zram0 device with the default settings [zram0]
Once booted, you can verify the swap device is set up by viewing the
swapon --show output. You can also view the true compression ratio of the currently configured zram devices by running