NAME
nbdkit-pattern-plugin - plugin to serve a fixed pattern of data for testing
SYNOPSIS
nbdkit pattern [size=]SIZE
DESCRIPTION
"nbdkit-pattern-plugin" is a plugin for nbdkit(1) which serves a fixed pattern of data, read only. This is used for testing nbdkit filters and NBD clients. To create test disks filled with other repeated patterns use nbdkit-data-plugin(1) or nbdkit-ones-plugin(1) instead.
The fixed pattern is the offset, as a 64 bit big endian integer, every 8 bytes. In hexadecimal this looks like:
offset data
0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 08
0010: 00 00 00 00 00 00 00 10 00 00 00 00 00 00 00 18
0020: 00 00 00 00 00 00 00 20 00 00 00 00 00 00 00 28
↗
└──────────┬──────────┘
byte at offset 0x28 │
│
64 bit big endian int
encoding offset 0x28
The size of the virtual disk must be specified using the "size" parameter. If the size is not a multiple of 8 then the last 8 byte offset in the pattern is truncated.
Largest
possible size
nbdkit itself limits plugins to 2⁶³-1 bytes
(decimal: 9223372036854775807,
hexadecimal: 0x7fff_ffff_ffff_ffff).
To test if NBD clients are free of bugs (not to mention nbdkit itself) you can use:
nbdkit pattern 9223372036854775807
Note this is too large for qemu to open.
Little
endian pattern
To get a little endian pattern instead of big endian apply
nbdkit-swab-filter(1) on top of this plugin:
nbdkit pattern 1G --filter=swab swab-bits=64
PARAMETERS
[size=]SIZE
Specify the virtual size of the disk image.
This parameter is required.
"size=" is a magic config key and may be omitted in most cases. See "Magic parameters" in nbdkit(1).
FILES
$plugindir/nbdkit-pattern-plugin.so
The plugin.
Use "nbdkit --dump-config" to find the location of $plugindir.
VERSION
"nbdkit-pattern-plugin" first appeared in nbdkit 1.6.
SEE ALSO
nbdkit(1), nbdkit-plugin(3), nbdkit-data-plugin(1), nbdkit-full-plugin(1), nbdkit-null-plugin(1), nbdkit-ones-plugin(1), nbdkit-offset-filter(1), nbdkit-random-plugin(1), nbdkit-sparse-random-plugin(1), nbdkit-swab-filter(1), nbdkit-zero-plugin(1).
AUTHORS
Richard W.M. Jones
COPYRIGHT
Copyright Red Hat
LICENSE
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
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