Provided by: util-linux_2.34-0.1ubuntu9_amd64 bug


       zramctl - set up and control zram devices


       Get info:

            zramctl [options]

       Reset zram:

            zramctl -r zramdev...

       Print name of first unused zram device:

            zramctl -f

       Set up a zram device:

            zramctl [-f | zramdev] [-s size] [-t number] [-a algorithm]


       zramctl  is  used  to quickly set up zram device parameters, to reset zram devices, and to
       query the status of used zram devices.

       If no option is given, all non-zero size zram devices are shown.

       Note that zramdev node specified on command line has to already exist. The command zramctl
       creates  a  new  /dev/zram<N>  nodes only when --find option specified. It's possible (and
       common) that after system boot /dev/zram<N> nodes are not created yet.


       -a, --algorithm lzo|lz4|lz4hc|deflate|842
              Set the compression algorithm to be used for compressing data in the zram device.

       -f, --find
              Find the first  unused  zram  device.   If  a  --size  argument  is  present,  then
              initialize the device.

       -n, --noheadings
              Do not print a header line in status output.

       -o, --output list
              Define  the  status  output  columns  to  be  used.   If  no  output arrangement is
              specified, then a default set is used.  Use --help to get a list of  all  supported

              Output all available columns.

       --raw  Use the raw format for status output.

       -r, --reset
              Reset  the  options  of  the specified zram device(s).  Zram device settings can be
              changed only after a reset.

       -s, --size size
              Create a zram device of the specified size.  Zram devices  are  aligned  to  memory
              pages;  when  the  requested  size  is  not a multiple of the page size, it will be
              rounded up to the next multiple.  When not otherwise specified,  the  unit  of  the
              size parameter is bytes.

              The  size  argument may be followed by the multiplicative suffixes KiB (=1024), MiB
              (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is  optional,
              e.g.,  "K"  has  the  same  meaning  as  "KiB")  or  the  suffixes  KB  (=1000), MB
              (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.

       -t, --streams number
              Set the maximum number of compression streams that can be used for the device.  The
              default is one stream.

       -V, --version
              Display version information and exit.

       -h, --help
              Display help text and exit.


       zramctl returns 0 on success, nonzero on failure.


              zram block devices


       The following commands set up a zram device with a size of one gigabyte and use it as swap

              # zramctl --find --size 1024M
              # mkswap /dev/zram0
              # swapon /dev/zram0
              # swapoff /dev/zram0
              # zramctl --reset /dev/zram0


       Linux kernel documentation ⟨


       Timofey Titovets <>
       Karel Zak <>


       The   zramctl   command   is  part  of  the  util-linux  package  and  is  available  from