NAME | SYNOPSIS | DESCRIPTION | COMMAND LINE OPTIONS | DATA REDUCTION | FILES | PCP ENVIRONMENT | SEE ALSO | DIAGNOSTICS | CAVEATS | COLOPHON

PMLOGREDUCE(1)             General Commands Manual            PMLOGREDUCE(1)

NAME         top

       pmlogreduce - temporal reduction of Performance Co-Pilot archives

SYNOPSIS         top

       $PCP_BINADM_DIR/pmlogreduce [-z] [-A align] [-S starttime] [-s
       samples] [-T endtime] [-t interval] [-v volsamples] [-Z timezone]
       input output

DESCRIPTION         top

       pmlogreduce reads one set of Performance Co-Pilot (PCP) archives
       identified by input and creates a temporally reduced PCP archive in
       output.  input is a comma-separated list of names, each of which may
       be the base name of an archive or the name of a directory containing
       one or more archives.  The data reduction involves statistical and
       temporal reduction of samples with an output sampling interval
       defined by the -t option in the output archive (independent of the
       sampling intervals in the input archives), and is further controlled
       by other command line arguments.

       For some metrics, temporal data reduction is not going to be helpful,
       so for metrics with types PM_TYPE_AGGREGATE or PM_TYPE_EVENT, a
       warning is issued if these metrics are found in input and they will
       be skipped and not appear in the output archive.

COMMAND LINE OPTIONS         top

       The command line options for pmlogreduce are as follows:

       -A align
              Specify a ``natural'' alignment of the output sample times;
              refer to PCPIntro(1).

       -S starttime
              Define the start of a time window to restrict the samples
              retrieved from the input archives; refer to PCPIntro(1).

       -s samples
              The argument samples defines the number of samples to be
              written to output.  If samples is 0 or -s is not specified,
              pmlogreduce will sample until the end of the set of PCP
              archives, or the end of the time window as specified by -T,
              whichever comes first.  The -s option will override the -T
              option if it occurs sooner.

       -T endtime
              Define the termination of a time window to restrict the
              samples retrieved from the input archives; refer to
              PCPIntro(1).

       -v volsamples
              The output archive is potentially a multi-volume data set, and
              the -v option causes pmlogreduce to start a new volume after
              volsamples log records have been written to the output
              archive.

              Independent of any -v option, each volume of an archive is
              limited to no more than 2^31 bytes, so pmlogreduce will
              automatically create a new volume for the archive before this
              limit is reached.

       -t interval
              Consecutive samples in the output archive will appear with a
              time delta defined by interval; refer to PCPIntro(1).  Note
              the default value is 600 (seconds, i.e. 10 minutes).

       -Z timezone
              Use timezone when displaying the date and time, or
              interpreting the -S and -T options.  Timezone is in the format
              of the environment variable TZ as described in environ(7).

       -z     Use the local timezone of the host from the input archives
              when displaying the date and time, or interpreting the -S and
              -T options.  The default is to initially use the timezone of
              the local host.

DATA REDUCTION         top

       The statistical and temporal reduction follows the following rules:

       1.  Consecutive records from input are read without interpolation,
           and at most one output record is written for each interval,
           summarizing the performance data over that period.

       2.  If the semantics of a metric indicates it is instantaneous or
           discrete then output value is computed as the arithmetic mean of
           the observations (if any) over each interval.

       3.  If the semantics of a metric indicates it is a counter then the
           following transformations are applied:
           a)  Metrics with 32-bit precision are promoted to 64-bit
               precision.
           b)  Any counter wrap (overflow) is noted, and appropriate
               adjustment made in the value of the metric over each
               interval.  This will be correct in the case of a single
               counter wrap, but will silently underestimate in the case
               where more than one counter wrap occurs between consecutive
               observations in the input archives, and silently overestimate
               in the case where a counter is reset occurs between
               consecutive observations in the input archives; unfortunately
               these situations cannot be detected, but are believed to be
               rare events for the sort of production monitoring
               environments where pmlogreduce is most likely to be deployed.

       4.  Any changes in instance domains, and indeed all metadata, is
           preserved.

       5.  Any ``mark'' records in the input archives (as created by
           pmlogextract(1)) will be preserved in the output archive, so
           periods where no data is available are maintained, and data
           interpolation will not occur across these periods when the output
           archive is subsequently processed with PCP applications.

FILES         top

       For each of the input and output archives, several physical files are
       used.
       archive.meta
                 metadata (metric descriptions, instance domains, etc.) for
                 the archive log
       archive.0 initial volume of metrics values (subsequent volumes have
                 suffixes 1, 2, ...) - for input these files may have been
                 previously compressed with bzip2(1) or gzip(1) and thus may
                 have an additional .bz2 or .gz suffix.
       archive.index
                 temporal index to support rapid random access to the other
                 files in the archive log.

PCP ENVIRONMENT         top

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

SEE ALSO         top

       PCPIntro(1), pmdumplog(1), pmlc(1), pmlogextract(1), pmlogger(1),
       pcp.conf(5) and pcp.env(5).

DIAGNOSTICS         top

       All error conditions detected by pmlogreduce are reported on stderr
       with textual (if sometimes terse) explanation.

       Should the input archives be corrupted (this can happen if the
       pmlogger instance writing the archive suddenly dies), then
       pmlogreduce will detect and report the position of the corruption in
       the file, and any subsequent information from the input archives will
       not be processed.

       If any error is detected, pmlogreduce will exit with a non-zero
       status.

CAVEATS         top

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

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
       Information about the project can be found at ⟨http://www.pcp.io/⟩.
       If you have a bug report for this manual page, send it to
       pcp@oss.sgi.com.  This page was obtained from the project's upstream
       Git repository ⟨git://git.pcp.io/pcp⟩ on 2017-05-03.  If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page, or
       you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a mail
       to man-pages@man7.org

Performance Co-Pilot                 PCP                      PMLOGREDUCE(1)

Pages that refer to this page: pmlogextract(1)pmlogrewrite(1)pmmgr(1)pcp-archive(5)