Manpages

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:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

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Neither the name of Red Hat nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

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