nbdkit-delay-filter(1)

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

6       nbdkit-delay-filter - nbdkit delay filter
7

SYNOPSIS

9        nbdkit --filter=delay plugin rdelay=SECS wdelay=SECS [plugin-args...]
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11        nbdkit --filter=delay plugin rdelay=NNms wdelay=NNms [plugin-args...]
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13        nbdkit --filter=delay plugin [plugin-args ...]
14                 delay-read=(SECS|NNms)
15                 delay-write=(SECS|NNms)
16                 delay-zero=(SECS|NNms)
17                 delay-trim=(SECS|NNms)
18                 delay-extents=(SECS|NNms)
19                 delay-cache=(SECS|NNms)
20                 delay-fast-zero=BOOL
21                 delay-open=(SECS|NNms)
22                 delay-close=(SECS|NNms)
23

DESCRIPTION

25       "nbdkit-delay-filter" is a filter that delays read and write requests
26       by some seconds or milliseconds.  This is used to simulate a slow or
27       remote server, or to test certain kinds of race conditions in Linux.
28       To limit server bandwidth use nbdkit-rate-filter(1) instead.
29

EXAMPLES

31       Delays reads and writes by 100ms:
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33        nbdkit --filter=delay file disk.img rdelay=100ms wdelay=100ms
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35       Delay only zero operations by 1 second, nothing else is affected:
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37        nbdkit --filter=delay file disk.img delay-zero=1
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PARAMETERS

40       rdelay=SECS
41       rdelay=NNms
42       delay-read=SECS
43       delay-read=NNms
44           Delay read operations by "SECS" seconds or "NN" milliseconds.
45
46           The two forms "rdelay" and "delay-read" work identically.
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48       delay-write=SECS
49       delay-write=NNms
50           Delay write operations by "SECS" seconds or "NN" milliseconds.
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52       delay-zero=SECS
53       delay-zero=NNms
54           (nbdkit ≥ 1.10)
55
56           Delay zero operations by "SECS" seconds or "NN" milliseconds.  See
57           also delay-fast-zero.
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59       delay-trim=SECS
60       delay-trim=NNms
61           (nbdkit ≥ 1.10)
62
63           Delay trim/discard operations by "SECS" seconds or "NN"
64           milliseconds.
65
66       delay-extents=SECS
67       delay-extents=NNms
68           (nbdkit ≥ 1.12)
69
70           Delay block status (extents) operations by "SECS" seconds or "NN"
71           milliseconds.
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73       delay-cache=SECS
74       delay-cache=NNms
75           (nbdkit ≥ 1.14)
76
77           Delay advisory cache operations by "SECS" seconds or "NN"
78           milliseconds.
79
80       wdelay=SECS
81       wdelay=NNms
82           Delay write, zero and trim operations by "SECS" seconds or "NN"
83           milliseconds.
84
85       delay-fast-zero=BOOL
86           (nbdkit ≥ 1.16)
87
88           The NBD specification documents an extension called fast zero, in
89           which the client may request that a server should reply with
90           "ENOTSUP" as soon as possible if the zero operation offers no real
91           speedup over a corresponding write.  By default, this parameter is
92           true, and fast zero requests are serviced by the plugin after the
93           same delay as any other zero request; but setting this parameter to
94           false instantly fails a fast zero response without waiting for or
95           consulting the plugin.
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97       delay-open=SECS
98       delay-open=NNms
99           (nbdkit ≥ 1.28)
100
101           Delay open (client connection) by "SECS" seconds or "NN"
102           milliseconds.
103
104       delay-close=SECS
105       delay-close=NNms
106           (nbdkit ≥ 1.28)
107
108           Delay close (client disconnection) by "SECS" seconds or "NN"
109           milliseconds.  This can also cause server shutdown to be delayed if
110           clients are connected at the time.  This only affects clients that
111           gracefully disconnect (using "NBD_CMD_DISC" / libnbd function
112           nbd_shutdown(3)).  Clients that abruptly disconnect from the server
113           cannot be delayed.
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FILES

116       $filterdir/nbdkit-delay-filter.so
117           The filter.
118
119           Use "nbdkit --dump-config" to find the location of $filterdir.
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VERSION

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

130       Richard W.M. Jones
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COPYRIGHT

133       Copyright (C) 2018-2021 Red Hat Inc.
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LICENSE

136       Redistribution and use in source and binary forms, with or without
137       modification, are permitted provided that the following conditions are
138       met:
139
140       •   Redistributions of source code must retain the above copyright
141           notice, this list of conditions and the following disclaimer.
142
143       •   Redistributions in binary form must reproduce the above copyright
144           notice, this list of conditions and the following disclaimer in the
145           documentation and/or other materials provided with the
146           distribution.
147
148       •   Neither the name of Red Hat nor the names of its contributors may
149           be used to endorse or promote products derived from this software
150           without specific prior written permission.
151
152       THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY
153       EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
154       IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
155       PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE
156       LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
157       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
158       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
159       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
160       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
161       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
162       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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166nbdkit-1.28.2                     2021-11-09            nbdkit-delay-filter(1)