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

6       nbdkit-log-filter - nbdkit log filter
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SYNOPSIS

9        nbdkit --filter=log plugin logfile=FILE [logappend=BOOL] [plugin-args...]
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DESCRIPTION

12       "nbdkit-log-filter" is a filter that logs all transactions.  When used
13       as the first filter, it can show the original client requests; as a
14       later filter, it can show how earlier filters have modified the
15       original request.  The log results are placed in a user-specified file;
16       for more details on the log format, see FILES.  Note that using "nbdkit
17       -v -f" produces much more verbose logging details to stderr about every
18       aspect of nbdkit operation, although this requires running nbdkit in
19       the foreground; while the log filter is designed to work even when
20       nbdkit is run as a daemon.
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PARAMETERS

23       The nbdkit-log-filter requires a single parameter "logfile" which
24       specifies the path of the file to use for logging.  If the file already
25       exists, it will be truncated unless the "logappend" parameter was
26       specified with a value that can be parsed as a boolean true.
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EXAMPLES

29       Serve the file disk.img, and log each client transaction in the file
30       disk.log:
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32        nbdkit --filter=log file disk.img logfile=disk.log
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34       Repeat the task, but with the cow (copy-on-write) filter to perform
35       local caching of data served from the original plugin:
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37        nbdkit --filter=cow --filter=log file disk.img logfile=disk.log2
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39       After running a client that performs the same operations under each of
40       the two servers, you can compare disk.log and disk.log2 to see the
41       impact of the caching.
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FILES

44       This filter writes to the file specified by the "logfile=FILE"
45       parameter.  All lines include a timestamp, a connection counter, then
46       details about the command.  The following actions are logged: Connect,
47       Read, Write, Zero, Trim, Extents, Flush, and Disconnect.  Except for
48       Connect and Disconnect, an event is logged across two lines for call
49       and return value, to allow tracking duration and tracing any parallel
50       execution, using id for correlation (incremented per action on the
51       connection).
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53       An example logging session of a client that performs a single
54       successful read is:
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56        2018-01-27 20:38:22.959984 connection=1 Connect size=0x400 write=1 flush=1 rotational=0 trim=0 zero=1 fua=1
57        2018-01-27 20:38:23.001720 connection=1 Read id=1 offset=0x0 count=0x100 ...
58        2018-01-27 20:38:23.001995 connection=1 ...Read id=1 return=0 (Success)
59        2018-01-27 20:38:23.044259 connection=1 Disconnect transactions=1
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SEE ALSO

62       nbdkit(1), nbdkit-file-plugin(1), nbdkit-cow-filter(1),
63       nbdkit-filter(3).
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AUTHORS

66       Eric Blake
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69       Copyright (C) 2018 Red Hat Inc.
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LICENSE

72       Redistribution and use in source and binary forms, with or without
73       modification, are permitted provided that the following conditions are
74       met:
75
76       ·   Redistributions of source code must retain the above copyright
77           notice, this list of conditions and the following disclaimer.
78
79       ·   Redistributions in binary form must reproduce the above copyright
80           notice, this list of conditions and the following disclaimer in the
81           documentation and/or other materials provided with the
82           distribution.
83
84       ·   Neither the name of Red Hat nor the names of its contributors may
85           be used to endorse or promote products derived from this software
86           without specific prior written permission.
87
88       THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY
89       EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
90       IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
91       PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE
92       LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
93       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
94       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
95       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
96       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
97       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
98       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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102nbdkit-1.12.3                     2019-05-21              nbdkit-log-filter(1)
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