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A wrapper script for the zram kernel module with interactive and init support

(C) Martin Väth (martin at Many thanks to all people in the AUTHORS file for contributing. The license of this package is the GNU Public License GPL-2. SPDX-License-Identifier: GPL-2.0-only

This is a small helper script to setup a zram device as swap or as a ramdisk. Also a zsh completion file and openrc and systemd init-scripts are provided.

General instructions

If zramctl (from >=util-linux-2.26) is available, this is used by default. Currently, this is not a dependency: a manual method is provided as a fallback. The latter might be removed in a future release of this script.

If you want to use one of the options -K -M -2 -Z to pass generic args, you need (v2.0 or newer) in your $PATH, see

To install this script, just copy the content of sbin into root's $PATH. To obtain support for zsh completion, copy the content of zsh to zsh's $fpath. For openrc support, the content of openrc should go into /etc. For systemd support, the content of systemd/system should go into a systemd unit directory (pkg-config --variable=systemdsystemunitdir systemd, usually /lib/systemd/system or /usr/lib/systemd/system) and be modified and enabled with systemctl enable ... for the desired setting. (Or install locally, e.g. directly into /etc/systemd/system). For systemd and optionally also for openrc the content of modprobe.d should go into /lib/modprobe.d or /etc/modprobe.d and be modified appropriately.

To use LZ4 compression with zram your kernel needs to be compiled with a corresponding options. Depending on your kernel version this might be

  • CONFIG_ZRAM_LZ4_COMPRESS=y (for older kernels)
  • CONFIG_CRYPTO_LZ4=y (for recent kernels)

Instructions for specific distributions


To install this script, you should use:

make install # for installation to /usr/local
make PREFIX=/usr install  # /usr instead of /usr/local

Gentoo based

There is an ebuild in the main gentoo tree (usually an older version) and in the mv overlay (current version).

Alpine Linux

A zram-init package is available.

Arch based

To install on Arch based distribution: install zram-init-git from AUR

Once installed, configure:

sudo cp /usr/lib/systemd/system/zram* /etc/systemd/system/
  • Lets make your configuration tweaks in

  • start

      sudo systemctl start zram_swap.service
      sudo systemctl start zram_tmp.service
      sudo systemctl start zram_var_tmp.service
  • and finaly enable

      sudo systemctl enable zram_swap.service
      sudo systemctl enable zram_tmp.service
      sudo systemctl enable zram_var_tmp.service

Optional remove any swap references in /etc/fstab