NAME | SYNOPSIS | DESCRIPTION | REPORT | FILES | PCP ENVIRONMENT | SEE ALSO | DIAGNOSTICS | COLOPHON

PCP-IOSTAT(1)              General Commands Manual             PCP-IOSTAT(1)

NAME         top

       pmiostat, pcp-iostat - performance metrics i/o statistics tool

SYNOPSIS         top

       pcp iostat [-A align --align=TIME] [-a archive --archive=FILE] [-G
       method --aggregate=method] [-h host --host=HOST] [-O offset
       --origin=TIME] [-S starttime --start=TIME] [-s samples --samples=N]
       [-T endtime --finish=TIME] [-t interval --interval=DELTA] [-P
       precision --precision=N] [-R pattern --regex=pattern] [-u --no-
       interpolate] [-Z timezone --timezone=TZ] [-z --hostzone] [-? --help]
       [-x [dm][,t][,h][,noidle]]

DESCRIPTION         top

       pcp-iostat reports I/O statistics for scsi devices (by default) or
       device-mapper devices (if the -x dm option is specified).  By default
       pcp-iostat reports live data for the local host but can also report
       for a remote host (-h) or from a previously captured PCP archive
       (-a).

       The -S, -T, -O and -A options may be used to define a time window to
       restrict the samples retrieved, set an initial origin within the time
       window, or specify a ``natural'' alignment of the sample times; refer
       to PCPIntro(1) for a complete description of these options.

       The other options which control the source, timing and layout of the
       information reported by pcp-iostat are as follows:

       -a   Performance metric values are retrieved from the Performance Co-
            Pilot (PCP) archive log files identified by the argument
            archive, which 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. See also -u.

       -G   Specifies that statistics for device names matching the regular
            expression specified with the -R regex option should be
            aggregated according to method.  Note this is aggregation based
            on matching device names (not temporal aggregation).  When -G is
            used, the device name column is reported as method(regex), e.g.
            if -G sum -R 'sd(a|b)$' is specified, the device column will be
            sum(sd(a|b)$) and summed statistics for sda and sdb will be
            reported in the remaining columns.  If -G is specified but -R is
            not specified, then the default regex is .*, i.e. matching all
            device names.  If method is sum then the statistics are summed.
            This includes the %util column, which may therefore exceed 100%
            if more than one device name matches.  If method is avg then the
            statistics are summed and then averaged by dividing by the
            number of matching device names.  If method is min or max, the
            minimum or maximum statistics for matching devices are reported,
            respectfully.

       -h   Current performance metric values are retrieved from the
            nominated host machine.

       -s   The argument samples defines the number of samples to be
            retrieved and reported.  If samples is 0 or -s is not specified,
            pcp-iostat will sample and report continuously (in real time
            mode) or until the end of the set of PCP archives (in archive
            mode).

       -t   The default update interval may be set to something other than
            the default 1 second.  The interval argument follows the syntax
            described in PCPIntro(1), and in the simplest form may be an
            unsigned integer (the implied units in this case are seconds).
            The -t option is particularly useful when replaying large sets
            of archives (-a option) that span several hours or even days.
            In this case specifying a large interval (e.g. 1h for 1 hour)
            will reduce the volume of data reported and the i/o statistics
            will be averaged (interpolated) over the reporting interval
            (unless the -u option is specified, see below).

       -R   This restricts the report to device names matching regex.  The
            regex pattern is searched as a perl style regular expression,
            and will match any portion of a device name.  e.g. '^sd[a-zA-
            Z]+' will match all device names starting with 'sd' followed by
            one or more alphabetic characters.  e.g. '^sd(a|b)$' will only
            match 'sda' and 'sdb'.  e.g. 'sda$' will match 'sda' but not
            'sdab'.  See also the -G option for aggregation options.

       -P   This indicates the number of decimals to print. The default
            precision N may be set to something other than the default 2
            decimals.  Note that the avgrq-sz and avgqu-sz fields are always
            reported with N+1 decimals of precision.  These fields typically
            have values less than 1.0.

       -u   When replaying a set of archives, by default values are reported
            according to the selected sample interval (-t option), not
            according to the actual record intervals in the set of archives.
            To this effect PCP interpolates the values to be reported based
            on the records in the set of archives, and is particularly
            useful when the -t option is used to replay a set of archives
            with a longer sampling interval than the underlying interval the
            set of archives was originally recorded with.  With the -u
            option, uninterpolated reporting is enabled - every value is
            reported according to the native recording interval in the set
            of archives.  When the -u option is specified, the -t option
            makes no sense and is incompatible because the replay interval
            is always the same as the recording interval in the set of
            archive.  In addition, -u only makes sense when replaying a set
            of archives, see -a above, and so if -u is specified then -a
            must also be specified.

       -Z   By default, pcp-iostat reports the time of day according to the
            local timezone on the system where pcp-iostat is run.  The -Z
            option changes the timezone to timezone in the format of the
            environment variable TZ as described in environ(7).

       -z   Change the reporting timezone to the local timezone at the host
            that is the source of the performance metrics, as identified via
            either the -h or -a options.  When replaying a PCP archive that
            was captured in a foreign timezone, the -z option would almost
            always be used (the default reporting timezone is the local
            timezone, which may not be the same as the timezone of the PCP
            archive).

       -x   Specifies a comma separated list of one or more extended
            reporting options as follows:
            dm - report statistics for device-mapper logical devices instead
            of scsi devices,
            t - prefix every line in the report with a timestamp in ctime(3)
            format,
            h - omit the heading, which is otherwise reported every 24
            samples,
            noidle - Do not display statistics for idle devices.

REPORT         top

       The columns in the pcp-iostat report have the following
       interpretation :

       Timestamp
              When the -x t option is specified, this column is the
              timestamp in ctime(3) format.

       Device Specifies the scsi device name, or if -x dm is specified, the
              device-mapper logical device name.  When -G is specified, this
              is replaced by the aggregation method and regular expression -
              see the -G and -R options above.

       rrqm/s The number of read requests expressed as a rate per-second
              that were merged during the reporting interval by the I/O
              scheduler.

       wrqm/s The number of write requests expressed as a rate per-second
              that were merged during the reporting interval by the I/O
              scheduler.

       r/s    The number of read requests completed by the device (after
              merges), expressed as a rate per second during the reporting
              interval.

       w/s    The number of write requests completed by the device (after
              merges), expressed as a rate per second during the reporting
              interval.

       rkB/s  The average volume of data read from the device expressed as
              KBytes/second during the reporting interval.

       wkB/s  The average volume of data written to the device expressed as
              KBytes/second during the reporting interval.

       avgrq-sz
              The average I/O request size for both reads and writes to the
              device expressed as Kbytes during the reporting interval.

       avgqu-sz
              The average queue length of read and write requests to the
              device during the reporting interval.

       await  The average time in milliseconds that read and write requests
              were queued (and serviced) to the device during the reporting
              interval.

       r_await
              The average time in milliseconds that read requests were
              queued (and serviced) to the device during the reporting
              interval.

       w_await
              The average time in milliseconds that write requests were
              queued (and serviced) to the device during the reporting
              interval.

       %util  The percentage of time during the reporting interval that the
              device was busy processing requests.  A value of 100%
              indicates device saturation.

FILES         top

       $PCP_VAR_DIR/pmns/*
                 default PMNS specification files

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

       pcp(1), PCPIntro(1), iostat2pcp(1), pmcd(1), pmchart(1), pmlogger(1),
       pcp.conf(5) and pcp.env(5).

DIAGNOSTICS         top

       All are generated on standard error and are intended to be self-
       explanatory.

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 2017-03-13.  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                       PCP-IOSTAT(1)