NAME

       zramctl - set up and control zram devices

SYNOPSIS

       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]

DESCRIPTION

       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.

OPTIONS

       -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 columns.

       --output-all
              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.

RETURN VALUE

       zramctl returns 0 on success, nonzero on failure.

FILES

       /dev/zram[0..N]
              zram block devices

EXAMPLE

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

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

SEE ALSO

       Linux kernel documentation.

AUTHORS

       Timofey Titovets <nefelim4ag@gmail.com>
       Karel Zak <kzak@redhat.com>

AVAILABILITY

       The   zramctl   command   is   part   of   the    util-linux    package    and    is    available    from
       https://www.kernel.org/pub/linux/utils/util-linux/.

util-linux                                          July 2014                                         ZRAMCTL(8)