NAME

       nbdkit-file-plugin - nbdkit file plugin

SYNOPSIS

        nbdkit file [file=]FILENAME

DESCRIPTION

       "nbdkit-file-plugin" is a file serving plugin for nbdkit(1).

       It serves the named "FILENAME" over NBD.  Local block devices (eg. /dev/sda) may also be
       served.

       To concatenate multiple files, use nbdkit-split-plugin(1).

       If you want to expose a file that resides on a file system known to have poor lseek(2)
       performance when searching for holes ("tmpfs" is known to be one such file system), you
       can use nbdkit-noextents-filter(1) to avoid the penalty of probing for holes.

PARAMETERS

       [file=]FILENAME
           Serve the file named "FILENAME".  A local block device name can also be used here.

           This parameter is required.

           "file=" is a magic config key and may be omitted in most cases.  See "Magic
           parameters" in nbdkit(1).

       rdelay
       wdelay
           These plugin parameters have been moved to the nbdkit-delay-filter(1) filter.  Modify
           the command line to add --filter=delay in order to use these parameters.

DUMP-PLUGIN OUTPUT

       You can obtain extra information about how the file plugin was compiled by doing:

        nbdkit file --dump-plugin

       Some of the fields which may appear are listed below.  Note these are for information only
       and may be changed or removed at any time in the future.

       "file_blksszget=yes"
       "file_blkzeroout=yes"
           If both set, the plugin may be able to efficiently zero ranges of block devices, where
           the driver and block device itself supports this.

       "file_falloc_fl_punch_hole=yes"
           If set, the plugin may be able to punch holes (make sparse) files and block devices.

       "file_falloc_fl_zero_range=yes"
           If set, the plugin may be able to efficiently zero ranges of files and block devices.

DEBUG FLAG

       -D file.zero=1
           This enables very verbose debugging of the NBD zero request.  This can be used to tell
           if the file plugin is able to zero ranges in the file or block device efficiently or
           not.

FILES

       $plugindir/nbdkit-file-plugin.so
           The plugin.

           Use "nbdkit --dump-config" to find the location of $plugindir.

VERSION

       "nbdkit-file-plugin" first appeared in nbdkit 1.0.

SEE ALSO

       nbdkit(1), nbdkit-plugin(3), nbdkit-split-plugin(1), nbdkit-partitioning-plugin(1),
       nbdkit-noextents-filter(1).

AUTHORS

       Eric Blake

       Nir Soffer

       Richard W.M. Jones

COPYRIGHT

       Copyright (C) 2013-2018 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.

       THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED
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