nbdkit-file-plugin - Man Page

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-tmpdisk-plugin(1), nbdkit-noextents-filter(1).

Authors

Eric Blake

Nir Soffer

Richard W.M. Jones

License

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Referenced By

nbdkit(1), nbdkit-cache-filter(1), nbdkit-cow-filter(1), nbdkit-delay-filter(1), nbdkit-error-filter(1), nbdkit-eval-plugin(1), nbdkit-floppy-plugin(1), nbdkit-fua-filter(1), nbdkit-iso-plugin(1), nbdkit-linuxdisk-plugin(1), nbdkit-log-filter(1), nbdkit-loop(1), nbdkit-memory-plugin(1), nbdkit-nocache-filter(1), nbdkit-noextents-filter(1), nbdkit-noparallel-filter(1), nbdkit-nozero-filter(1), nbdkit-offset-filter(1), nbdkit-partition-filter(1), nbdkit-partitioning-plugin(1), nbdkit-plugin(3), nbdkit-release-notes-1.6(1), nbdkit-split-plugin(1), nbdkit-tmpdisk-plugin(1), nbdkit-truncate-filter(1), nbdkit-xz-filter(1), virt-p2v(1).

2020-05-26 nbdkit-1.21.4