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.

       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.

SEE ALSO

       nbdkit(1), nbdkit-plugin(3), nbdkit-data-plugin(1), nbdkit-full-plugin(1),
       nbdkit-null-plugin(1), nbdkit-offset-filter(1), nbdkit-random-plugin(1),
       nbdkit-zero-plugin(1).

AUTHORS

       Richard W.M. Jones

COPYRIGHT

       Copyright (C) 2018 Red Hat Inc.

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.

       ·   Redistributions in binary form must reproduce the above copyright notice, this list of
           conditions and the following disclaimer in the documentation and/or other materials
           provided with the distribution.

       ·   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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