zramctl(8)

1ZRAMCTL(8)                   System Administration                  ZRAMCTL(8)
2
3
4

NAME

6       zramctl - set up and control zram devices
7

SYNOPSIS

9       Get info:
10
11            zramctl [options]
12
13       Reset zram:
14
15            zramctl -r zramdev...
16
17       Print name of first unused zram device:
18
19            zramctl -f
20
21       Set up a zram device:
22
23            zramctl [-f | zramdev] [-s size] [-t number] [-a algorithm]
24
25

DESCRIPTION

27       zramctl is used to quickly set up zram device parameters, to reset zram
28       devices, and to query the status of used zram devices.
29
30       If no option is given, all non-zero size zram devices are shown.
31
32       Note that zramdev node specified on command line has to already  exist.
33       The  command  zramctl creates a new /dev/zram<N> nodes only when --find
34       option specified. It's possible (and common)  that  after  system  boot
35       /dev/zram<N> nodes are not created yet.
36

OPTIONS

38       -a, --algorithm lzo|lz4|lz4hc|deflate|842
39              Set the compression algorithm to be used for compressing data in
40              the zram device.
41
42       -f, --find
43              Find the first unused zram device.   If  a  --size  argument  is
44              present, then initialize the device.
45
46       -n, --noheadings
47              Do not print a header line in status output.
48
49       -o, --output list
50              Define  the  status  output  columns  to  be used.  If no output
51              arrangement is specified, then  a  default  set  is  used.   Use
52              --help to get a list of all supported columns.
53
54       --output-all
55              Output all available columns.
56
57       --raw  Use the raw format for status output.
58
59       -r, --reset
60              Reset  the options of the specified zram device(s).  Zram device
61              settings can be changed only after a reset.
62
63       -s, --size size
64              Create a zram device of the specified size.   Zram  devices  are
65              aligned to memory pages; when the requested size is not a multi‐
66              ple of the page size, it will be rounded up to the  next  multi‐
67              ple.  When not otherwise specified, the unit of the size parame‐
68              ter is bytes.
69
70              The size argument may be followed by the multiplicative suffixes
71              KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB,
72              ZiB and YiB (the "iB" is optional, e.g., "K" has the same  mean‐
73              ing  as  "KiB") or the suffixes KB (=1000), MB (=1000*1000), and
74              so on for GB, TB, PB, EB, ZB and YB.
75
76       -t, --streams number
77              Set the maximum number of compression streams that can  be  used
78              for the device.  The default is one stream.
79
80       -V, --version
81              Display version information and exit.
82
83       -h, --help
84              Display help text and exit.
85
86

RETURN VALUE

88       zramctl returns 0 on success, nonzero on failure.
89
90

FILES

92       /dev/zram[0..N]
93              zram block devices
94
95

EXAMPLE

97       The following commands set up a zram device with a size of one gigabyte
98       and use it as swap device.
99
100              # zramctl --find --size 1024M
101              /dev/zram0
102              # mkswap /dev/zram0
103              # swapon /dev/zram0
104               ...
105              # swapoff /dev/zram0
106              # zramctl --reset /dev/zram0
107

AUTHORS

113       Timofey Titovets <nefelim4ag@gmail.com>
114       Karel Zak <kzak@redhat.com>
115

AVAILABILITY

117       The  zramctl command is part of the util-linux package and is available
118       from https://www.kernel.org/pub/linux/utils/util-linux/.
119
120
121
122util-linux                         July 2014                        ZRAMCTL(8)