xenial (8) zramctl.8.gz

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 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.

       --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 <nefelim4ag@gmail.com>
       Karel Zak <kzak@redhat.com>

AVAILABILITY

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