pmlogreduce(1)
NAME
pmlogreduce - temporal reduction of Performance Co-Pilot archives
SYNOPSIS
$PCP_BINADM_DIR/pmlogreduce [-z] [-A align] [-S starttime] [-s samples] [-T endtime] [-t interval] [-v volsamples] [-Z timezone] input output
DESCRIPTION
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
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
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
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
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
PCPIntro(1), pmdumplog(1), pmlc(1), pmlogextract(1), pmlogger(1), pcp.conf(5) and pcp.env(5).
DIAGNOSTICS
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
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.
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
