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nbdkit-delay-filter(1)		    NBDKIT		nbdkit-delay-filter(1)

NAME
       nbdkit-delay-filter - nbdkit delay filter

SYNOPSIS
	nbdkit --filter=delay plugin rdelay=SECS wdelay=SECS [plugin-args...]

	nbdkit --filter=delay plugin rdelay=NNms wdelay=NNms [plugin-args...]

	nbdkit --filter=delay plugin [plugin-args ...]
		 delay-read=(SECS|NNms)	delay-write=(SECS|NNms)
		 delay-zero=(SECS|NNms)	delay-trim=(SECS|NNms)
		 delay-extents=(SECS|NNms) delay-cache=(SECS|NNms)
		 delay-fast-zero=BOOL

DESCRIPTION
       "nbdkit-delay-filter" is	a filter that delays read and write requests
       by some seconds or milliseconds.	 This is used to simulate a slow or
       remote server, or to test certain kinds of race conditions in Linux.
       To limit	server bandwidth use nbdkit-rate-filter(1) instead.

EXAMPLES
       Delays reads and	writes by 100ms:

	nbdkit --filter=delay file disk.img rdelay=100ms wdelay=100ms

       Delay only zero operations by 1 second, nothing else is affected:

	nbdkit --filter=delay file disk.img delay-zero=1

PARAMETERS
       rdelay=SECS
       rdelay=NNms
       delay-read=SECS
       delay-read=NNms
	   Delay read operations by "SECS" seconds or "NN" milliseconds.

	   The two forms "rdelay" and "delay-read" work	identically.

       delay-write=SECS
       delay-write=NNms
	   Delay write operations by "SECS" seconds or "NN" milliseconds.

       delay-zero=SECS
       delay-zero=NNms
	   Delay zero operations by "SECS" seconds or "NN" milliseconds.  See
	   also	delay-fast-zero.

       delay-trim=SECS
       delay-trim=NNms
	   Delay trim/discard operations by "SECS" seconds or "NN"
	   milliseconds.

       delay-extents=SECS
       delay-extents=NNms
	   Delay block status (extents)	operations by "SECS" seconds or	"NN"
	   milliseconds.

       delay-cache=SECS
       delay-cache=NNms
	   Delay advisory cache	operations by "SECS" seconds or	"NN"
	   milliseconds.

       wdelay=SECS
       wdelay=NNms
	   Delay write,	zero and trim operations by "SECS" seconds or "NN"
	   milliseconds.

       delay-fast-zero=BOOL
	   The NBD specification documents an extension	called fast zero, in
	   which the client may	request	that a server should reply with
	   "ENOTSUP" as	soon as	possible if the	zero operation offers no real
	   speedup over	a corresponding	write.	By default, this parameter is
	   true, and fast zero requests	are serviced by	the plugin after the
	   same	delay as any other zero	request; but setting this parameter to
	   false instantly fails a fast	zero response without waiting for or
	   consulting the plugin.

FILES
       $filterdir/nbdkit-delay-filter.so
	   The filter.

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

VERSION
       "nbdkit-delay-filter" first appeared in nbdkit 1.2, based on earlier
       "rdelay"	and "wdelay" options in	nbdkit-file-plugin(1).

SEE ALSO
       nbdkit(1), nbdkit-filter(3), nbdkit-rate-filter(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:

       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-delay-filter(1)

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

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