noble (1) nbdkit-delay-filter.1.gz

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
                 delay-open=(SECS|NNms)
                 delay-close=(SECS|NNms)

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
           (nbdkit ≥ 1.10)

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

       delay-trim=SECS
       delay-trim=NNms
           (nbdkit ≥ 1.10)

           Delay trim/discard operations by "SECS" seconds or "NN" milliseconds.

       delay-extents=SECS
       delay-extents=NNms
           (nbdkit ≥ 1.12)

           Delay block status (extents) operations by "SECS" seconds or "NN" milliseconds.

       delay-cache=SECS
       delay-cache=NNms
           (nbdkit ≥ 1.14)

           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
           (nbdkit ≥ 1.16)

           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.

       delay-open=SECS
       delay-open=NNms
           (nbdkit ≥ 1.28)

           Delay open (client connection) by "SECS" seconds or "NN" milliseconds.

       delay-close=SECS
       delay-close=NNms
           (nbdkit ≥ 1.28)

           Delay close (client disconnection) by "SECS" seconds or "NN" milliseconds.  This can also cause
           server shutdown to be delayed if clients are connected at the time.  This only affects clients that
           gracefully disconnect (using "NBD_CMD_DISC" / libnbd function nbd_shutdown(3)).  Clients that
           abruptly disconnect from the server cannot be delayed.

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-pause-filter(1), nbdkit-rate-filter(1).

AUTHORS

       Richard W.M. Jones

COPYRIGHT

       Copyright Red Hat

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 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
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