1PMLOGREDUCE(1) General Commands Manual PMLOGREDUCE(1)
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6 pmlogreduce - temporal reduction of Performance Co-Pilot archives
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9 $PCP_BINADM_DIR/pmlogreduce [-z] [-A align] [-S starttime] [-s samples]
10 [-T endtime] [-t interval] [-v volsamples] [-Z timezone] input output
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13 pmlogreduce reads one set of Performance Co-Pilot (PCP) archives iden‐
14 tified by input and creates a temporally reduced PCP archive in output.
15 input is a comma-separated list of names, each of which may be the base
16 name of an archive or the name of a directory containing one or more
17 archives. The data reduction involves statistical and temporal reduc‐
18 tion of samples with an output sampling interval defined by the -t
19 option in the output archive (independent of the sampling intervals in
20 the input archives), and is further controlled by other command line
21 arguments.
22 For some metrics, temporal data reduction is not going to be helpful,
24 so for metrics with types PM_TYPE_AGGREGATE or PM_TYPE_EVENT, a warning
25 is issued if these metrics are found in input and they will be skipped
26 and not appear in the output archive.
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29 The command line options for pmlogreduce are as follows:
30 -A align
32 Specify a ``natural'' alignment of the output sample times;
33 refer to PCPIntro(1).
34 -S starttime
36 Define the start of a time window to restrict the samples
37 retrieved from the input archives; refer to PCPIntro(1).
38 -s samples
40 The argument samples defines the number of samples to be written
41 to output. If samples is 0 or -s is not specified, pmlogreduce
42 will sample until the end of the set of PCP archives, or the end
43 of the time window as specified by -T, whichever comes first.
44 The -s option will override the -T option if it occurs sooner.
45 -T endtime
47 Define the termination of a time window to restrict the samples
48 retrieved from the input archives; refer to PCPIntro(1).
49 -v volsamples
51 The output archive is potentially a multi-volume data set, and
52 the -v option causes pmlogreduce to start a new volume after
53 volsamples log records have been written to the output archive.
54 Independent of any -v option, each volume of an archive is lim‐
56 ited to no more than 2^31 bytes, so pmlogreduce will automati‐
57 cally create a new volume for the archive before this limit is
58 reached.
59 -t interval
61 Consecutive samples in the output archive will appear with a
62 time delta defined by interval; refer to PCPIntro(1). Note the
63 default value is 600 (seconds, i.e. 10 minutes).
64 -Z timezone
66 Use timezone when displaying the date and time, or interpreting
67 the -S and -T options. Timezone is in the format of the envi‐
68 ronment variable TZ as described in environ(7).
69 -z Use the local timezone of the host from the input archives when
71 displaying the date and time, or interpreting the -S and -T
72 options. The default is to initially use the timezone of the
73 local host.
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76 The statistical and temporal reduction follows the following rules:
77 1. Consecutive records from input are read without interpolation, and
79 at most one output record is written for each interval, summarizing
80 the performance data over that period.
81 2. If the semantics of a metric indicates it is instantaneous or dis‐
83 crete then output value is computed as the arithmetic mean of the
84 observations (if any) over each interval.
85 3. If the semantics of a metric indicates it is a counter then the
87 following transformations are applied:
88 a) Metrics with 32-bit precision are promoted to 64-bit precision.
89 b) Any counter wrap (overflow) is noted, and appropriate adjust‐
90 ment made in the value of the metric over each interval. This
91 will be correct in the case of a single counter wrap, but will
92 silently underestimate in the case where more than one counter
93 wrap occurs between consecutive observations in the input ar‐
94 chives, and silently overestimate in the case where a counter
95 reset occurs between consecutive observations in the input ar‐
96 chives; unfortunately these situations cannot be detected, but
97 are believed to be rare events for the sort of production moni‐
98 toring environments where pmlogreduce is most likely to be
99 deployed.
100 4. Any changes in instance domains, and indeed all metadata, is pre‐
102 served.
103 5. Any ``mark'' records in the input archives (as created by pmlogex‐
105 tract(1)) will be preserved in the output archive, so periods where
106 no data is available are maintained, and data interpolation will
107 not occur across these periods when the output archive is subse‐
108 quently processed with PCP applications.
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111 For each of the input and output archives, several physical files are
112 used.
113 archive.meta
114 metadata (metric descriptions, instance domains, etc.) for
115 the archive log
116 archive.0 initial volume of metrics values (subsequent volumes have
117 suffixes 1, 2, ...) - for input these files may have been
118 previously compressed with bzip2(1) or gzip(1) and thus may
119 have an additional .bz2 or .gz suffix.
120 archive.index
121 temporal index to support rapid random access to the other
122 files in the archive log.
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125 Environment variables with the prefix PCP_ are used to parameterize the
126 file and directory names used by PCP. On each installation, the file
127 /etc/pcp.conf contains the local values for these variables. The
128 $PCP_CONF variable may be used to specify an alternative configuration
129 file, as described in pcp.conf(5).
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132 PCPIntro(1), pmdumplog(1), pmlc(1), pmlogextract(1), pmlogger(1),
133 pcp.conf(5) and pcp.env(5).
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136 All error conditions detected by pmlogreduce are reported on stderr
137 with textual (if sometimes terse) explanation.
138 Should the input archives be corrupted (this can happen if the pmlogger
140 instance writing the archive suddenly dies), then pmlogreduce will
141 detect and report the position of the corruption in the file, and any
142 subsequent information from the input archives will not be processed.
143 If any error is detected, pmlogreduce will exit with a non-zero status.
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147 The preamble metrics (pmcd.pmlogger.archive, pmcd.pmlogger.host, and
148 pmcd.pmlogger.port), which are automatically recorded by pmlogger at
149 the start of the archive, may not be present in the archive output by
150 pmlogreduce. These metrics are only relevant while the archive is
151 being created, and have no significance once recording has finished.
152Performance Co-Pilot PCP PMLOGREDUCE(1)