1nbdkit-sparse-random-plugin(1)      NBDKIT      nbdkit-sparse-random-plugin(1)
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NAME

6       nbdkit-sparse-random-plugin - make sparse random disks
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SYNOPSIS

9        nbdkit sparse-random [size=]SIZE [seed=SEED] [percent=N] [runlength=N]
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DESCRIPTION

12       "nbdkit-sparse-random-plugin" is a plugin for nbdkit(1) which makes
13       disks containing sparse blocks of random data.  These disks have a
14       similar shape to virtual machine disks, and this plugin can be used to
15       benchmark disk copying tools like nbdcopy(1).  To get a non-sparse
16       random disk, see nbdkit-random-plugin(1).
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18       The size of the virtual disk must be specified using the "size"
19       parameter.  If you specify the "seed" parameter then you will get the
20       same random data over multiple runs with the same seed.
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22       The "percent" parameter controls the percentage of the disk which
23       contains random data versus sparse empty space.
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25       The plugin does not generate random data spread evenly over the disk.
26       Instead to make it look more like a real virtual machine disk, it tries
27       to create runs of data and runs of empty space.  The "runlength"
28       parameter controls the average length of each run of random data.
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30       The random data is generated using an insecure method.
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32   Writes and testing copying
33       Writes to the disk verify that the data written is the same as the data
34       read (if not, returning EIO).  Thus when testing copies you can use a
35       single instance of this plugin for both read and write:
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37        nbdkit -U - sparse-random size=1T --run 'nbdcopy "$uri" "$uri"'
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39       "qemu-img convert" could be used in place of nbdcopy.  See also
40       nbdkit-checkwrite-filter(1).
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PARAMETERS

43       percent=N
44           Specify the approximate percentage of the disk which contains
45           random data versus sparse empty space.  The default is 10 (10%).
46           "percent=0" will create a completely empty disk and "percent=100"
47           will create a completely full disk.
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49       runlength=N
50           Specify the average length of runs of random data.  This is
51           expressed in bytes and the usual modifiers can be used.  The
52           default is 16M, meaning that (on average) data runs will be 16
53           megabytes in length.
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55       seed=SEED
56           Specify the random seed to get repeatable data over multiple runs.
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58           If not specified then a random seed is chosen.
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60       [size=]SIZE
61           Specify the virtual size of the disk image.
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63           This parameter is required.
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65           "size=" is a magic config key and may be omitted in most cases.
66           See "Magic parameters" in nbdkit(1).
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FILES

69       $plugindir/nbdkit-sparse-random-plugin.so
70           The plugin.
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72           Use "nbdkit --dump-config" to find the location of $plugindir.
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VERSION

75       "nbdkit-sparse-random-plugin" first appeared in nbdkit 1.24.
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SEE ALSO

78       nbdkit(1), nbdkit-plugin(3), nbdkit-data-plugin(1),
79       nbdkit-full-plugin(1), nbdkit-null-plugin(1), nbdkit-pattern-plugin(1),
80       nbdkit-random-plugin(1), nbdkit-zero-plugin(1), nbdcopy(1),
81       qemu-img(1).
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AUTHORS

84       Richard W.M. Jones
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87       Copyright (C) 2018 Red Hat Inc.
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LICENSE

90       Redistribution and use in source and binary forms, with or without
91       modification, are permitted provided that the following conditions are
92       met:
93
94       •   Redistributions of source code must retain the above copyright
95           notice, this list of conditions and the following disclaimer.
96
97       •   Redistributions in binary form must reproduce the above copyright
98           notice, this list of conditions and the following disclaimer in the
99           documentation and/or other materials provided with the
100           distribution.
101
102       •   Neither the name of Red Hat nor the names of its contributors may
103           be used to endorse or promote products derived from this software
104           without specific prior written permission.
105
106       THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY
107       EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
108       IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
109       PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE
110       LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
111       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
112       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
113       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
114       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
115       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
116       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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120nbdkit-1.25.8                     2021-05-25    nbdkit-sparse-random-plugin(1)
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