zramctl

ZRAMCTL(8)                   System Administration                  ZRAMCTL(8)

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 ar-
              rangement 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 multi-
              ple of the page size, it will be rounded up to the  next  multi-
              ple.  When not otherwise specified, the unit of the size parame-
              ter 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  mean-
              ing  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 <http://git.kernel.org/cgit/linux/kernel/git
       /torvalds/linux.git/tree/Documentation/blockdev/zram.txt>.

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)