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nbdkit-memory-plugin(1)		    NBDKIT	       nbdkit-memory-plugin(1)

NAME
       nbdkit-memory-plugin - nbdkit virtual memory (RAM disk) plugin

SYNOPSIS
	nbdkit memory [size=]SIZE

DESCRIPTION
       "nbdkit-memory-plugin" is a plugin for nbdkit(1)	which stores a single
       disk image in virtual memory, and discards it when nbdkit exits.	 This
       plugin can be used for testing or where you don't care about the	final
       content of the disk image.

       All nbdkit clients will see the same disk content, initially all
       zeroes.

       The disk	image is stored	in memory using	a sparse array.	 The allocated
       parts of	the disk image cannot be larger	than physical RAM plus swap,
       less whatever is	being used by the rest of the system.  If you want to
       allocate	more space than	this use nbdkit-file-plugin(1) backed by a
       temporary file instead.

       However the virtual size	can be as large	as you like, up	to the maximum
       supported by nbdkit (2a<paragraph>A^3-1A	bytes).	 This limit is tested
       when nbdkit is compiled,	and it should work on all platforms and
       architectures supported by nbdkit.

EXAMPLES
       Create a	one gigabyte sparse RAM	disk:

	nbdkit memory 1G

       If you want to loop mount the above disk, see nbdkit-loop(1).

       Create the largest possible RAM disk:

	nbdkit memory $(( 2**63	- 1 ))

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).

NOTES
   Preloading small amounts of data
       If you want an in-memory	disk image preinitialized with a small amount
       of data specified on the	command	line, look at nbdkit-data-plugin(1)
       instead.	 Note by "small" this does not mean that the virtual disk
       image must be small, but	that the amount	of data	initially stored
       sparsely	is small enough	to specify on the command line.

   Preloading large amounts of data
       If you want to preload a	large amount of	data (eg. a disk image)	into
       the memory plugin, use qemu-img(1):

	$ rm -f	pid
	$ nbdkit -P pid	memory 10G

	# wait for nbdkit to become ready to accept connections:
	$ while	[ ! -f pid ]; do sleep 1; done

	# preload Fedora disk image:
	$ virt-builder fedora-28 --size=10G
	$ qemu-img convert -p -n fedora-28.img nbd:localhost:10809

FILES
       $plugindir/nbdkit-memory-plugin.so
	   The plugin.

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

VERSION
       "nbdkit-memory-plugin" first appeared in	nbdkit 1.2.

SEE ALSO
       nbdkit(1), nbdkit-plugin(3), nbdkit-loop(1), nbdkit-data-plugin(1),
       nbdkit-file-plugin(1), nbdkit-info-plugin(1), nbdkit-tmpdisk-plugin(1).

AUTHORS
       Richard W.M. Jones

COPYRIGHT
       Copyright (C) 2017-2020 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:

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

       o   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.

       o   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 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.

nbdkit-1.20.4			  2021-03-01	       nbdkit-memory-plugin(1)

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | PARAMETERS | NOTES | FILES | VERSION | SEE ALSO | AUTHORS | COPYRIGHT | LICENSE

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