From Fedora Project Wiki


Test installation of zram-generator and zram-generator-defaults (enables swap-on-zram by default)

How to test

  1. We recommend to remove the following packages. The swap-on-zram implementations in those packages have minor conflicts with zram-generator, but mostly they'll just contribute to user confusion.
    sudo dnf remove anaconda zram
  2. Install zram-generator and zram-generator-defaults:
    sudo dnf install zram-generator zram-generator-defaults
  3. Reboot your machine
  4. Verify that swap-on-zram is active. zramctl should list the /dev/zram0 device and show it mounted as [SWAP]. Example:
    $ zramctl 
    /dev/zram0 lzo-rle       1.4G   4K   74B   12K       2 [SWAP]
  5. Verify that the size of the device in the output above (DISKSIZE column) has a size equal to 50% of installed memory, or 4 GiB, whichever is smaller.
  6. Verify that swapon lists the /dev/zram0 device. Example:
    $ swapon 
    /dev/vda1  partition 500M   0B   -2
    /dev/zram0 partition 1.4G   0B  100

    If you have another swap device present, like in the example above, that is not a problem. Unless you configured your swap priority manually, your pre-existing swap device should have a lower priority than the new /dev/zram0 device.

  7. Verify the service unit file is marked as "active (exited)" and its output looks OK with no errors or issues listed.
    $ sudo systemctl status swap-create@zram0.service
    ● swap-create@zram0.service - Create swap on /dev/zram0
         Loaded: loaded (/usr/lib/systemd/system/swap-create@.service; static; vendor preset: disabled)
         Active: active (exited) since Sun 2020-06-28 19:24:57 MDT; 36s ago
           Docs: man:zram-generator(8)
        Process: 646 ExecStart=/usr/lib/systemd/system-generators/zram-generator --setup-device zram0 (code=exited, status=0/SUCCESS)
       Main PID: 646 (code=exited, status=0/SUCCESS)
            CPU: 32ms
    Jun 28 19:24:57 fmac.local systemd[1]: Starting Create swap on /dev/zram0...
    Jun 28 19:24:57 fmac.local zram-generator[648]: Setting up swapspace version 1, size = 3.8 GiB (4105170944 bytes)
    Jun 28 19:24:57 fmac.local zram-generator[648]: no label, UUID=03831cdf-96df-4a7a-a6c2-3bc8406f33f3
    Jun 28 19:24:57 fmac.local systemd[1]: Finished Create swap on /dev/zram0.

Expected Results

  1. The zram-generator and zram-generator-defaults are installed without issues, and the feature is automatically activated after a reboot with the proper size. It should have a size equal to 50% of installed memory, or 4GiB, whichever is smaller.