1nbdkit-error-filter(1) NBDKIT nbdkit-error-filter(1)
2
6 nbdkit-error-filter - inject errors for testing clients
7
9 nbdkit --filter=error PLUGIN
10 [error=EPERM|EIO|ENOMEM|EINVAL|ENOSPC|ESHUTDOWN]
11 [error-rate=10%|0.1]
12 [error-file=/tmp/inject]
13 [error-pread=...] [error-pread-rate=...] [error-pread-file=...]
14 [error-pwrite=...] [error-pwrite-rate=...] [error-pwrite-file=...]
15 [error-trim=...] [error-trim-rate=...] [error-trim-file=...]
16 [error-zero=...] [error-zero-rate=...] [error-zero-file=...]
17 [error-extents=...] [error-extents-rate=...] [error-extents-file=...]
18 [error-cache=...] [error-cache-rate=...] [error-cache-file=...]
19
21 "nbdkit-error-filter" is an nbdkit filter that injects random errors
22 into replies from the server. This is used for testing that NBD
23 clients can handle errors.
24 All parameters are optional, but you should usually specify one of the
26 "error-rate" or "error-*-rate" parameters, otherwise this filter will
27 do nothing.
28
30 Inject a low rate of errors randomly into the connection:
31 nbdkit --filter=error file disk.img error-rate=1%
33 Reading, trimming, cache and extents (block status) requests will be
35 successful, but all writes and zeroing will return "No space left on
36 device":
37 nbdkit --filter=error file disk.img \
39 error=ENOSPC \
40 error-pwrite-rate=100% \
41 error-zero-rate=100%
42 To make all connections fail hard 60 seconds after the server is
44 started, use:
45 rm -f /tmp/inject
47 nbdkit --filter=error file disk.img \
48 error-rate=100% \
49 error-file=/tmp/inject
50 sleep 60; touch /tmp/inject
51
53 error=EPERM|EIO|ENOMEM|EINVAL|ENOSPC|ESHUTDOWN
54 When a random error is injected, you can select which one from the
55 range of possible NBD errors (the NBD protocol only supports a
56 limited range of error codes).
57 This parameter is optional and the default is "EIO" ("Input/output
59 error").
60 error-rate=N%
62 error-rate=0..1
63 The rate of injected errors per NBD request. This can be expressed
64 as either a percentage between "0%" and "100%" or as a probability
65 between 0 and 1. If "0%" or 0 is used then no errors are ever
66 injected, and if "100%" or 1 is used then all requests return
67 errors.
68 This parameter is optional and the default is "0%". Unless you set
70 this, the filter will do nothing.
71 error-file=FILENAME
73 Errors will only be injected when FILENAME exists. (Note you must
74 also specify the "error-rate").
75 You can use this for fine-grained control over when to inject
77 errors, for example if you want to trigger an error at an exact
78 moment during a test, arrange for this file to be created at the
79 appropriate time. Or conversely to test error recovery in a
80 client, create the file initially, and then delete it to check the
81 client can recover.
82 This parameter is optional.
84 error-pread, error-pread-rate, error-pread-file.
86 Same as "error", "error-rate" and "error-file" but only apply the
87 settings to NBD pread requests.
88 error-pwrite, error-pwrite-rate, error-pwrite-file.
90 Same as "error", "error-rate" and "error-file" but only apply the
91 settings to NBD pwrite requests.
92 error-trim, error-trim-rate, error-trim-file.
94 Same as "error", "error-rate" and "error-file" but only apply the
95 settings to NBD trim requests.
96 error-zero, error-zero-rate, error-zero-file.
98 Same as "error", "error-rate" and "error-file" but only apply the
99 settings to NBD zero requests.
100 error-extents, error-extents-rate, error-extents-file.
102 (nbdkit ≥ 1.12)
103 Same as "error", "error-rate" and "error-file" but only apply the
105 settings to NBD block status requests to read extents.
106 error-cache, error-cache-rate, error-cache-file.
108 (nbdkit ≥ 1.14)
109 Same as "error", "error-rate" and "error-file" but only apply the
111 settings to NBD cache requests.
112
114 Peculiar debug output
115 If you are looking at the debugging output (using "nbdkit -f -v")
116 references to the name of this filter show up as "error-inject:", and
117 such lines indicate that the filter is not altering output, for
118 example:
119 nbdkit: file.9: debug: error-inject: pread count=1024 offset=0 flags=0x0
121 Conversely, references to the string "error:" occur when the
123 nbdkit_error(3) API was used, including when this filter injects an
124 error, as in:
125 nbdkit: file.4: error: injecting ENOSPC error into pwrite
127
129 $filterdir/nbdkit-error-filter.so
130 The filter.
131 Use "nbdkit --dump-config" to find the location of $filterdir.
133
135 "nbdkit-error-filter" first appeared in nbdkit 1.6.
136
138 nbdkit(1), nbdkit-file-plugin(1), nbdkit-full-plugin(1),
139 nbdkit-retry-filter(1), nbdkit-retry-request-filter(1),
140 nbdkit-filter(3).
141
143 Richard W.M. Jones
144
146 Copyright (C) 2018 Red Hat Inc.
147
149 Redistribution and use in source and binary forms, with or without
150 modification, are permitted provided that the following conditions are
151 met:
152 • Redistributions of source code must retain the above copyright
154 notice, this list of conditions and the following disclaimer.
155 • Redistributions in binary form must reproduce the above copyright
157 notice, this list of conditions and the following disclaimer in the
158 documentation and/or other materials provided with the
159 distribution.
160 • Neither the name of Red Hat nor the names of its contributors may
162 be used to endorse or promote products derived from this software
163 without specific prior written permission.
164 THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY
166 EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
167 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
168 PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE
169 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
170 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
171 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
172 BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
173 WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
174 OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
175 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
176nbdkit-1.32.5 2023-01-03 nbdkit-error-filter(1)