Ubuntu Manpage: pmlogextract - reduce, extract, concatenate and merge Performance Co-Pilot archives

NAME

       pmlogextract - reduce, extract, concatenate and merge Performance Co-Pilot archives

SYNOPSIS

       pmlogextract  [-dfmwxz?]   [-c  configfile]  [-S  starttime] [-s samples] [-T endtime] [-v
       volsamples] [-Z timezone] input [...] output

DESCRIPTION

       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.

OPTIONS

The available command line options are:

-c config, --config=config
Extract only the metrics specified in config from the input PCP archive log(s). The
config syntax accepted by pmlogextract is explained in more detail in the
Configuration File Syntax section.

-d, --desperate
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, --first
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, --mark
As described in the MARK RECORDS section below, sometimes it is possible to safely
omit records from the output archive. If the -m option is specified, then the
epilogue and prologue test is skipped and a record will always be inserted at
the end of each input archive (except the last). This is the original behaviour for
pmlogextract.

-S starttime, --start=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, --samples=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, --finish=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 records to indicate the temporal
discontinuity between the end of one time window and the start of the next.

-x It is expected that the metadata (name, PMID, type, semantics and units) for each
metric will be consistent across all of the input PCP archive log(s) in which that
metric appears. In rare cases, e.g. in development, in QA and when a PMDA is
upgraded, this may not be the case and pmlogextract will report the issue and abort
without creating the output archive log. This is done so the problem can be fixed
with pmlogrewrite(1) before retrying the merge. In unattended or QA environments it
may be preferable to force the merge and omit the metrics with the mismatched
metadata. The -x option does this.

-Z timezone, --timezone=timezone
Use timezone when displaying the date and time. Timezone is in the format of the
environment variable TZ as described in environ(7). The default is to initially use
the timezone of the local host.

-z, --hostzone
Use the local timezone of the host from the input archive logs. The default is to
initially use the timezone of the local host.

-?, --help
Display usage message and exit.

CONFIGURATION FILE SYNTAX

       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.

CONFIGURATION FILE EXAMPLE

       This is an example of a valid configfile:

               #
               # config file for pmlogextract
               #

               kernel.all.cpu
               kernel.percpu.cpu.sys ["cpu0","cpu1"]
               disk.dev ["dks0d1"]

MARK RECORDS

When more than one input archive log contributes performance data to the output archive
log, then records may be inserted to indicate a possible discontinuity in the
performance data.

A 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 record can safely be
omitted from the output archive.

The rationale behind 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 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 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
 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 records in a PCP archive log can be established using pmdumplog(1)
where a timestamp and the annotation is used to indicate a record.

METADATA CHECKS

       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.

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 pmlogextract.  These metrics are only relevant while the
       archive is being created, and have no significance once recording has finished.

DIAGNOSTICS

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

       If one of the input archives contains no archive records then an ``empty archive'' warning
       is issued and that archive is skipped.

       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.

FILES

       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.

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).

       For environment variables affecting PCP tools, see pmGetOptions(3).