zramctl(8)

1ZRAMCTL(8)                   System Administration                  ZRAMCTL(8)
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NAME

6       zramctl - set up and control zram devices
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SYNOPSIS

9       Get info:
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11            zramctl [options]
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13       Reset zram:
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15            zramctl -r zramdev...
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17       Print name of first unused zram device:
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19            zramctl -f
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21       Set up a zram device:
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23            zramctl [-f | zramdev] [-s size] [-t number] [-a algorithm]
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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.
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30       If no option is given, all non-zero size zram devices are shown.
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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.
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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.
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42       -f, --find
43              Find the first unused zram device.   If  a  --size  argument  is
44              present, then initialize the device.
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46       -n, --noheadings
47              Do not print a header line in status output.
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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.
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54       --raw  Use the raw format for status output.
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56       -r, --reset
57              Reset  the options of the specified zram device(s).  Zram device
58              settings can be changed only after a reset.
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60       -s, --size size
61              Create a zram device of the specified size.   Zram  devices  are
62              aligned to memory pages; when the requested size is not a multi‐
63              ple of the page size, it will be rounded up to the  next  multi‐
64              ple.  When not otherwise specified, the unit of the size parame‐
65              ter is bytes.
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67              The size argument may be followed by the multiplicative suffixes
68              KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB,
69              ZiB and YiB (the "iB" is optional, e.g., "K" has the same  mean‐
70              ing  as  "KiB") or the suffixes KB (=1000), MB (=1000*1000), and
71              so on for GB, TB, PB, EB, ZB and YB.
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73       -t, --streams number
74              Set the maximum number of compression streams that can  be  used
75              for the device.  The default is one stream.
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77       -V, --version
78              Display version information and exit.
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80       -h, --help
81              Display help text and exit.
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RETURN VALUE

85       zramctl returns 0 on success, nonzero on failure.
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FILES

89       /dev/zram[0..N]
90              zram block devices
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EXAMPLE

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

110       Timofey Titovets <nefelim4ag@gmail.com>
111       Karel Zak <kzak@redhat.com>
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AVAILABILITY

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