1PMLOGREDUCE(1)              General Commands Manual             PMLOGREDUCE(1)
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NAME

6       pmlogreduce - temporal reduction of Performance Co-Pilot archives
7

SYNOPSIS

9       $PCP_BINADM_DIR/pmlogreduce  [-z?]   [-A align] [-s samples] [-S start‐
10       time] [-t interval] [-T endtime] [-v volsamples]  [-Z  timezone]  input
11       output
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DESCRIPTION

14       pmlogreduce  reads one set of Performance Co-Pilot (PCP) archives iden‐
15       tified by input and creates a temporally reduced PCP archive in output.
16       input is a comma-separated list of names, each of which may be the base
17       name of an archive or the name of a directory containing  one  or  more
18       archives.   The data reduction involves statistical and temporal reduc‐
19       tion of samples with an output sampling  interval  defined  by  the  -t
20       option  in the output archive (independent of the sampling intervals in
21       the input archives), and is further controlled by  other  command  line
22       arguments.
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24       For  some  metrics, temporal data reduction is not going to be helpful,
25       so for metrics with types PM_TYPE_AGGREGATE or PM_TYPE_EVENT, a warning
26       is  issued if these metrics are found in input and they will be skipped
27       and not appear in the output archive.
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OPTIONS

30       The available command line options are:
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32       -A align, --align=align
33            Specify a ``natural'' alignment of the output sample times;  refer
34            to PCPIntro(1).
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36       -s samples, --samples=samples
37            The  argument  samples defines the number of samples to be written
38            to output.  If samples is 0 or -s is  not  specified,  pmlogreduce
39            will  sample  until the end of the set of PCP archives, or the end
40            of the time window as specified by -T, whichever comes first.  The
41            -s option will override the -T option if it occurs sooner.
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43       -S starttime, --start=starttime
44            Define  the  start  of  a  time  window  to  restrict  the samples
45            retrieved from the input archives; refer to PCPIntro(1).
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47       -t interval, --interval=interval
48            Consecutive samples in the output archive will appear with a  time
49            delta defined by interval; refer to PCPIntro(1).  Note the default
50            value is 600 (seconds, i.e. 10 minutes).
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52       -T endtime, --finish=endtime
53            Define the termination of a time window to  restrict  the  samples
54            retrieved from the input archives; refer to PCPIntro(1).
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56       -v volsamples
57            The output archive is potentially a multi-volume data set, and the
58            -v option causes pmlogreduce to start a new volume  after  volsam‐
59            ples log records have been written to the output archive.
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61              Independent  of any -v option, each volume of an archive is lim‐
62              ited to no more than 2^31 bytes, so pmlogreduce  will  automati‐
63              cally  create  a new volume for the archive before this limit is
64              reached.
65
66       -z, --hostzone
67            Use the local timezone of the host from the  input  archives  when
68            displaying  the  date  and  time,  or  interpreting  the -S and -T
69            options.  The default is to initially  use  the  timezone  of  the
70            local host.
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72       -Z timezone, --timezone=timezone
73            Use  timezone  when  displaying the date and time, or interpreting
74            the -S and -T options.  Timezone is in the format of the  environ‐
75            ment variable TZ as described in environ(7).
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77       -?, --help
78            Display usage message and exit.
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DATA REDUCTION

81       The statistical and temporal reduction follows the following rules:
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83       1.  Consecutive  records from input are read without interpolation, and
84           at most one output record is written for each interval, summarizing
85           the performance data over that period.
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87       2.  If  the semantics of a metric indicates it is instantaneous or dis‐
88           crete then output value is computed as the arithmetic mean  of  the
89           observations (if any) over each interval.
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91       3.  If  the  semantics  of  a metric indicates it is a counter then the
92           following transformations are applied:
93           a)  Metrics with 32-bit precision are promoted to 64-bit precision.
94           b)  Any counter wrap (overflow) is noted, and  appropriate  adjust‐
95               ment  made in the value of the metric over each interval.  This
96               will be correct in the case of a single counter wrap, but  will
97               silently  underestimate in the case where more than one counter
98               wrap occurs between consecutive observations in the  input  ar‐
99               chives,  and  silently overestimate in the case where a counter
100               reset occurs between consecutive observations in the input  ar‐
101               chives;  unfortunately these situations cannot be detected, but
102               are believed to be rare events for the sort of production moni‐
103               toring  environments  where  pmlogreduce  is  most likely to be
104               deployed.
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106       4.  Any changes in instance domains, and indeed all metadata,  is  pre‐
107           served.
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109       5.  Any  ``mark'' records in the input archives (as created by pmlogex‐
110           tract(1)) will be preserved in the output archive, so periods where
111           no  data  is  available are maintained, and data interpolation will
112           not occur across these periods when the output  archive  is  subse‐
113           quently processed with PCP applications.
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CAVEATS

116       The  preamble  metrics  (pmcd.pmlogger.archive, pmcd.pmlogger.host, and
117       pmcd.pmlogger.port), which are automatically recorded  by  pmlogger  at
118       the  start  of the archive, may not be present in the archive output by
119       pmlogreduce.  These metrics are only  relevant  while  the  archive  is
120       being created, and have no significance once recording has finished.
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DIAGNOSTICS

123       All  error  conditions  detected  by pmlogreduce are reported on stderr
124       with textual (if sometimes terse) explanation.
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126       Should the input archives be corrupted (this can happen if the pmlogger
127       instance  writing  the  archive  suddenly  dies), then pmlogreduce will
128       detect and report the position of the corruption in the file,  and  any
129       subsequent information from the input archives will not be processed.
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131       If any error is detected, pmlogreduce will exit with a non-zero status.
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FILES

134       For  each  of the input and output archives, several physical files are
135       used.
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137       archive.meta
138            metadata (metric descriptions, instance domains, etc.) for the ar‐
139            chive log
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141       archive.0
142            initial volume of metrics values (subsequent volumes have suffixes
143            1, 2, ...) - for input these files may have been  previously  com‐
144            pressed  with  bzip2(1) or gzip(1) and thus may have an additional
145            .bz2 or .gz suffix.
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147       archive.index
148            temporal index to support rapid random access to the  other  files
149            in the archive log.
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PCP ENVIRONMENT

152       Environment variables with the prefix PCP_ are used to parameterize the
153       file and directory names used by PCP.  On each installation,  the  file
154       /etc/pcp.conf  contains  the  local  values  for  these variables.  The
155       $PCP_CONF variable may be used to specify an alternative  configuration
156       file, as described in pcp.conf(5).
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SEE ALSO

159       PCPIntro(1),   pmdumplog(1),   pmlc(1),  pmlogextract(1),  pmlogger(1),
160       pcp.conf(5) and pcp.env(5).
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164Performance Co-Pilot                  PCP                       PMLOGREDUCE(1)
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