Provided by: nbdkit_1.24.1-2ubuntu4_amd64 
NAME
nbdkit-error-filter - inject errors for testing clients
SYNOPSIS
nbdkit --filter=error PLUGIN
[error=EPERM|EIO|ENOMEM|EINVAL|ENOSPC|ESHUTDOWN]
[error-rate=10%|0.1]
[error-file=/tmp/inject]
[error-pread=...] [error-pread-rate=...] [error-pread-file=...]
[error-pwrite=...] [error-pwrite-rate=...] [error-pwrite-file=...]
[error-trim=...] [error-trim-rate=...] [error-trim-file=...]
[error-zero=...] [error-zero-rate=...] [error-zero-file=...]
[error-extents=...] [error-extents-rate=...] [error-extents-file=...]
[error-cache=...] [error-cache-rate=...] [error-cache-file=...]
DESCRIPTION
"nbdkit-error-filter" is an nbdkit filter that injects random errors into replies from the server. This
is used for testing that NBD clients can handle errors.
All parameters are optional, but you should usually specify one of the "error-rate" or "error-*-rate"
parameters, otherwise this filter will do nothing.
EXAMPLES
Inject a low rate of errors randomly into the connection:
nbdkit --filter=error file disk.img error-rate=1%
Reading, trimming, cache and extents (block status) requests will be successful, but all writes and
zeroing will return "No space left on device":
nbdkit --filter=error file disk.img \
error=ENOSPC \
error-pwrite-rate=100% \
error-zero-rate=100%
To make all connections fail hard 60 seconds after the server is started, use:
rm -f /tmp/inject
nbdkit --filter=error file disk.img \
error-rate=100% \
error-file=/tmp/inject
sleep 60; touch /tmp/inject
PARAMETERS
error=EPERM|EIO|ENOMEM|EINVAL|ENOSPC|ESHUTDOWN
When a random error is injected, you can select which one from the range of possible NBD errors (the
NBD protocol only supports a limited range of error codes).
This parameter is optional and the default is "EIO" ("Input/output error").
error-rate=N%
error-rate=0..1
The rate of injected errors per NBD request. This can be expressed as either a percentage between
"0%" and "100%" or as a probability between 0 and 1. If "0%" or 0 is used then no errors are ever
injected, and if "100%" or 1 is used then all requests return errors.
This parameter is optional and the default is "0%". Unless you set this, the filter will do nothing.
error-file=FILENAME
Errors will only be injected when FILENAME exists. (Note you must also specify the "error-rate").
You can use this for fine-grained control over when to inject errors, for example if you want to
trigger an error at an exact moment during a test, arrange for this file to be created at the
appropriate time. Or conversely to test error recovery in a client, create the file initially, and
then delete it to check the client can recover.
This parameter is optional.
error-pread, error-pread-rate, error-pread-file.
Same as "error", "error-rate" and "error-file" but only apply the settings to NBD pread requests.
error-pwrite, error-pwrite-rate, error-pwrite-file.
Same as "error", "error-rate" and "error-file" but only apply the settings to NBD pwrite requests.
error-trim, error-trim-rate, error-trim-file.
Same as "error", "error-rate" and "error-file" but only apply the settings to NBD trim requests.
error-zero, error-zero-rate, error-zero-file.
Same as "error", "error-rate" and "error-file" but only apply the settings to NBD zero requests.
error-extents, error-extents-rate, error-extents-file.
(nbdkit ≥ 1.12)
Same as "error", "error-rate" and "error-file" but only apply the settings to NBD block status
requests to read extents.
error-cache, error-cache-rate, error-cache-file.
(nbdkit ≥ 1.14)
Same as "error", "error-rate" and "error-file" but only apply the settings to NBD cache requests.
NOTES
Peculiar debug output
If you are looking at the debugging output (using "nbdkit -f -v") then you may see peculiar "errors"
appearing when using this filter, for example:
nbdkit: file.9: debug: error: pread count=1024 offset=0 flags=0x0
In fact these are not errors, nbdkit core is simply printing the name of the filter which happens to be
"error". When this filter injects an error you will see something like:
nbdkit: file.4: error: injecting ENOSPC error into pwrite
FILES
$filterdir/nbdkit-error-filter.so
The filter.
Use "nbdkit --dump-config" to find the location of $filterdir.
VERSION
"nbdkit-error-filter" first appeared in nbdkit 1.6.
SEE ALSO
nbdkit(1), nbdkit-file-plugin(1), nbdkit-full-plugin(1), nbdkit-filter(3).
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:
• 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
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-1.24.1 2021-01-20 nbdkit-error-filter(1)