sys-utils/zramctl.8

   1 .TH ZRAMCTL 8 "July 2014" "util-linux" "System Administration"
   2 .SH NAME
   3 zramctl \- set up and control zram devices
   4 .SH SYNOPSIS
   5 .ad l
   6 Get info:
   7 .sp
   8 .in +5
   9 .BR zramctl " [options]"
  10 .sp
  11 .in -5
  12 Reset zram:
  13 .sp
  14 .in +5
  15 .B "zramctl \-r"
  16 .IR zramdev ...
  17 .sp
  18 .in -5
  19 Print name of first unused zram device:
  20 .sp
  21 .in +5
  22 .B "zramctl \-f"
  23 .sp
  24 .in -5
  25 Set up a zram device:
  26 .sp
  27 .in +5
  28 .B zramctl
  29 .RB [ \-f " | "\fIzramdev\fP ]
  30 .RB [ \-s
  31 .IR size ]
  32 .RB [ \-t
  33 .IR number ]
  34 .RB [ \-a
  35 .IR algorithm ]
  36 .sp
  37 .in -5
  38 .ad b
  39 .SH DESCRIPTION
  40 .B zramctl
  41 is used to quickly set up zram device parameters, to reset zram devices, and to
  42 query the status of used zram devices.
  43 .PP
  44 If no option is given, all non-zero size zram devices are shown.
  45 .PP
  46 Note that \fIzramdev\fP node specified on command line has to already exist. The command
  47 .B zramctl
  48 creates a new /dev/zram<N> nodes only when \fB\-\-find\fR option specified. It's possible
  49 (and common) that after system boot /dev/zram<N> nodes are not created yet.
  50 .SH OPTIONS
  51 .TP
  52 .BR \-a , " \-\-algorithm lzo" | lz4 | lz4hc | deflate | 842
  53 Set the compression algorithm to be used for compressing data in the zram device.
  54 .TP
  55 .BR \-f , " \-\-find"
  56 Find the first unused zram device.  If a \fB\-\-size\fR argument is present, then
  57 initialize the device.
  58 .TP
  59 .BR \-n , " \-\-noheadings"
  60 Do not print a header line in status output.
  61 .TP
  62 .BR \-o , " \-\-output " \fIlist
  63 Define the status output columns to be used.  If no output arrangement is
  64 specified, then a default set is used.
  65 Use \fB\-\-help\fP to get a list of all supported columns.
  66 .TP
  67 .B \-\-output\-all
  68 Output all available columns.
  69 .TP
  70 .B \-\-raw
  71 Use the raw format for status output.
  72 .TP
  73 .BR \-r , " \-\-reset"
  74 Reset the options of the specified zram device(s).  Zram device settings
  75 can be changed only after a reset.
  76 .TP
  77 .BR \-s , " \-\-size " \fIsize
  78 Create a zram device of the specified \fIsize\fR.
  79 Zram devices are aligned to memory pages; when the requested \fIsize\fR is
  80 not a multiple of the page size, it will be rounded up to the next multiple.
  81 When not otherwise specified, the unit of the \fIsize\fR parameter is bytes.
  82 .IP
  83 The \fIsize\fR argument may be followed by the multiplicative suffixes KiB (=1024),
  84 MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB"
  85 is optional, e.g., "K" has the same meaning as "KiB") or the suffixes
  86 KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.
  87 .TP
  88 .BR \-t , " \-\-streams " \fInumber
  89 Set the maximum number of compression streams that can be used for the device.
  90 The default is one stream.
  91 .TP
  92 .BR \-V , " \-\-version"
  93 Display version information and exit.
  94 .TP
  95 .BR \-h , " \-\-help"
  96 Display help text and exit.
  97
  98 .SH RETURN VALUE
  99 .B zramctl
 100 returns 0 on success, nonzero on failure.
 101
 102 .SH FILES
 103 .TP
 104 .I /dev/zram[0..N]
 105 zram block devices
 106
 107 .SH EXAMPLE
 108 The following commands set up a zram device with a size of one gigabyte
 109 and use it as swap device.
 110 .nf
 111 .IP
 112 # zramctl --find --size 1024M
 113 /dev/zram0
 114 # mkswap /dev/zram0
 115 # swapon /dev/zram0
 116  ...
 117 # swapoff /dev/zram0
 118 # zramctl --reset /dev/zram0
 119 .fi
 120 .SH SEE ALSO
 121 .UR http://git.\:kernel.\:org\:/cgit\:/linux\:/kernel\:/git\:/torvalds\:/linux.git\:/tree\:/Documentation\:/admin-guide\:/blockdev\:/zram.rst
 122 Linux kernel documentation
 123 .UE .
 124 .SH AUTHORS
 125 .nf
 126 Timofey Titovets <nefelim4ag@gmail.com>
 127 Karel Zak <kzak@redhat.com>
 128 .fi
 129 .SH AVAILABILITY
 130 The zramctl command is part of the util-linux package and is available from
 131 https://www.kernel.org/pub/linux/utils/util-linux/.