Provided by: pcp_4.3.1-1_amd64 bug

NAME

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

SYNOPSIS

       pmlogextract  [-dfmwz]  [-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 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.

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 <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.

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.

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).

SEE ALSO

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

DIAGNOSTICS

       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.

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.