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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 zram devices are shown.

OPTIONS
       -a, --algorithm lzo|lz4
              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  initial‐
              ize 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 speci‐
              fied, then a default set is used.  Use --help to get a list of all  supported  col‐
              umns.

       --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 ⟨http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git
       /tree/Documentation/blockdev/zram.txt⟩.

AUTHORS
       Timofey Titovets 
       Karel Zak 

AVAILABILITY
       The zramctl command is part of the util-linux package and is available from ftp://ftp.ker‐
       nel.org/pub/linux/utils/util-linux/.

util-linux                                  July 2014                                  ZRAMCTL(8)

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