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) 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.

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.

AUTHORS

Richard W.M. Jones

COPYRIGHT

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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