PMLOGEXTRACT(1) General Commands Manual PMLOGEXTRACT(1)
pmlogextract - reduce, extract, concatenate and merge Performance Co-
Pilot archives
pmlogextract [-dfmwz] [-c configfile] [-S starttime] [-s samples] [-T
endtime] [-v volsamples] [-Z timezone] input [...] output
pmlogextract reads one or more Performance Co-Pilot (PCP) archive
logs identified by input and creates a temporally merged and/or
reduced PCP archive log 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 nature of
merging is controlled by the number of input archive logs, while the
nature of data reduction is controlled by the command line arguments.
The input(s) must be sets of PCP archive logs created by pmlogger(1)
with performance data collected from the same host, but usually over
different time periods and possibly (although not usually) with
different performance metrics being logged.
If only one input is specified, then the default behavior simply
copies the input set of PCP archive logs, into the output PCP archive
log. When two or more sets of PCP archive logs are specified as
input, the sets of logs are merged (or concatenated) and written to
output.
In the output archive log a <mark> record may be inserted at a time
just past the end of each of the input archive logs to indicate a
possible temporal discontinuity between the end of one input archive
log and the start of the next input archive log. See the MARK
RECORDS section below for more information. There is no <mark>
record after the end of the last (in temporal order) of the input
archive logs.
The command line options for pmlogextract are as follows:
-c configfile
Extract only the metrics specified in configfile from the
input PCP archive log(s). The configfile syntax accepted by
pmlogextract is explained in more detail in the Configuration
File Syntax section.
-d Desperate mode. Normally if a fatal error occurs, all trace
of the partially written PCP archive output is removed. With
the -d option, the output archive log is not removed.
-f For most common uses, all of the input archive logs will have
been collected in the same timezone. But if this is not the
case, then pmlogextract must choose one of the timezones from
the input archive logs to be used as the timezone for the
output archive log. The default is to use the timezone from
the last input archive log. The -f option forces the timezone
from the first input archive log to be used.
-m As described in the MARK RECORDS section below, sometimes it
is possible to safely omit <mark> records from the output
archive. If the -m option is specified, then the epilogue and
prologue test is skipped and a <mark> record will always be
inserted at the end of each input archive (except the last).
This is the original behaviour for pmlogextract.
-S starttime
Define the start of a time window to restrict the samples
retrieved or specify a ``natural'' alignment of the output
sample times; refer to PCPIntro(1). See also the -w option.
-s samples
The argument samples defines the number of samples to be
written to output. If samples is 0 or -s is not specified,
pmlogextract will sample until the end of the PCP archive log,
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 or specify a ``natural'' alignment of the
output sample times; refer to PCPIntro(1). See also the -w
option.
-v volsamples
The output archive log is potentially a multi-volume data set,
and the -v option causes pmlogextract to start a new volume
after volsamples log records have been written to the archive
log.
Independent of any -v option, each volume of an archive is
limited to no more than 2^31 bytes, so pmlogextract will
automatically create a new volume for the archive before this
limit is reached.
-w Where -S and -T specify a time window within the same day, the
-w flag will cause the data within the time window to be
extracted, for every day in the archive log. For example, the
options -w -S @11:00 -T @15:00 specify that pmlogextract
should include archive log records only for the periods from
11am to 3pm on each day. When -w is used, the output archive
log will contain <mark> records to indicate the temporal
discontinuity between the end of one time window and the start
of the next.
-Z timezone
Use timezone when displaying the date and time. 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 archive
logs. The default is to initially use the timezone of the
local host.
The configfile contains metrics of interest - only those metrics (or
instances) mentioned explicitly or implicitly in the configuration
file will be included in the output archive. Each specifications
must begin on a new line, and may span multiple lines in the
configuration file. Instances may also be specified, but they are
optional. The format for each specification is
metric [[instance[,instance...]]]
where metric may be a leaf or a non-leaf name in the Performance
Metrics Name Space (PMNS, see pmns(5)). If a metric refers to a non-
leaf node in the PMNS, pmlogextract will recursively descend the PMNS
and include all metrics corresponding to descendent leaf nodes.
Instances are optional, and may be specified as a list of one or more
space (or comma) separated names, numbers or strings (enclosed in
single or double quotes). Elements in the list that are numbers are
assumed to be internal instance identifiers - see pmGetInDom(3) for
more information. If no instances are given, then all instances of
the associated metric(s) will be extracted.
Any additional white space is ignored and comments may be added with
a `#' prefix.
This is an example of a valid configfile:
#
# config file for pmlogextract
#
kernel.all.cpu
kernel.percpu.cpu.sys ["cpu0","cpu1"]
disk.dev ["dks0d1"]
When more than one input archive log contributes performance data to
the output archive log, then <mark> records may be inserted to
indicate a possible discontinuity in the performance data.
A <mark> record contains a timestamp and no performance data and is
used to indicate that there is a time period in the PCP archive log
where we do not know the values of any performance metrics, because
there was no pmlogger(1) collecting performance data during this
period. Since these periods are often associated with the restart of
a service or pmcd(1) or a system, there may be considerable doubt as
to the continuity of performance data across this time period.
Most current archives are created with a prologue record at the
beginning and an epilogue record at the end. These records identify
the state of pmcd(1) at the time, and may be used by pmlogextract to
determine that there is no discontinuity between the end of one
archive and the next output record, and as a consequence the <mark>
record can safely be omitted from the output archive.
The rationale behind <mark> records may be demonstrated with an
example. Consider one input archive log that starts at 00:10 and
ends at 09:15 on the same day, and another input archive log that
starts at 09:20 on the same day and ends at 00:10 the following
morning. This would be a very common case for archives managed and
rotated by pmlogger_check(1) and pmlogger_daily(1).
The output archive log created by pmlogextract would contain:
00:10.000 first record from first input archive log
...
09:15.000 last record from first input archive log
09:15.001 <mark> record
09:20.000 first record from second input archive log
...
01:10.000 last record from second input archive log
The time period where the performance data is missing starts just
after 09:15 and ends just before 09:20. When the output archive log
is processed with any of the PCP reporting tools, the <mark> record
is used to indicate a period of missing data. For example using the
output archive above, imagine one was reporting the average I/O rate
at 30 minute intervals aligned on the hour and half-hour. The I/O
count metric is a counter, so the average I/O rate requires two valid
values from consecutive sample times. There would be values for all
the intervals ending at 09:00, then no values at 09:30 because of the
<mark> record, then no values at 10:00 because the ``prior'' value at
09:30 is not available, then the rate would be reported again at
10:30 and continue every 30 minutes until the last reported value at
01:00.
The presence of <mark> records in a PCP archive log can be
established using pmdumplog(1) where a timestamp and the annotation
<mark> is used to indicate a <mark> record.
When more than one input archive set is specified, pmlogextract
performs a number of checks to ensure the metadata is consistent for
metrics appearing in more than one of the input archive sets. These
checks include:
* metric data type is the same
* metric semantics are the same
* metric units are the same
* metric is either always singular or always has the same instance
domain
* metrics with the same name have the same PMID
* metrics with the same PMID have the same name
If any of these checks fail, pmlogextract reports the details and
aborts without creating the output archive.
To address these semantic issues, use pmlogrewrite(1) to translate
the input archives into equivalent archives with consistent metdadata
before using pmlogextract.
For each of the input and output archive logs, 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.
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).
PCPIntro(1), pmdumplog(1), pmlc(1), pmlogger(1), pmlogreduce(1),
pmlogrewrite(1), pcp.conf(5) and pcp.env(5).
All error conditions detected by pmlogextract are reported on stderr
with textual (if sometimes terse) explanation.
Should one of the input archive logs be corrupted (this can happen if
the pmlogger instance writing the log suddenly dies), then
pmlogextract will detect and report the position of the corruption in
the file, and any subsequent information from that archive log will
not be processed.
If any error is detected, pmlogextract will exit with a non-zero
status.
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
pmlogextract. These metrics are only relevant while the archive is
being created, and have no significance once recording has finished.
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@groups.io. This page was obtained from the project's upstream
Git repository ⟨https://github.com/performancecopilot/pcp.git⟩ on
2018-02-02. (At that time, the date of the most recent commit that
was found in the repository was 2018-02-02.) 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 PMLOGEXTRACT(1)
Pages that refer to this page: ganglia2pcp(1), pcpintro(1), pmdumplog(1), pmdumptext(1), pmlogcheck(1), pmlogger_check(1), pmloglabel(1), pmlogreduce(1), pmlogrewrite(1), pmlogsummary(1), pmrep(1), sar2pcp(1), pmfetch(3), pmfetcharchive(3), LOGARCHIVE(5)
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