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

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

NAME         top

       pmiostat, pcp-iostat - report block I/O statistics

SYNOPSIS         top

       pcp [pcp options] iostat [-u] [-G method] [-P precision] [-R pattern]
       [-x [dm][,t][,h][,noidle]]

DESCRIPTION         top

       pcp-iostat reports I/O statistics for SCSI (by default) or other
       devices (if the -x option is specified).

       When invoked via the pcp(1) command, the -a/--archive, -h/--host,
       -O/--origin, -s/--samples, -t/--interval, -Z/--timezone and several
       other pcp options become indirectly available; refer to PCPIntro(1)
       for a complete description of these options.

OPTIONS         top

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

       -G method, --aggregate=method
            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,
            respectively.

       -P N, --precision=N
            This indicates the precision (number of decimal places) to
            report.  The default precision N may be set to something other
            than the default (2).  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.

       -R pattern, --regex=pattern
            This restricts the report to device names matching a regular
            expression pattern.  The given 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.

       -u, --no-interpolation
            When replaying a set of archives, by default values are reported
            according to the requested sample interval (-t option), not
            according to the actual interval recorded in the archive(s).
            Without this option PCP interpolates the values to be reported
            based on the records in the set of archives, which is
            particularly useful when the -t option is used to replay a set
            of archives with a longer sampling interval than that with which
            the archive(s) 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
            archives, see the -a option on PCPIntro(1), and so if -u is
            specified then -a must also be specified.

       -x comma-separated-options
            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.

DIAGNOSTICS         top

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

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).

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

SEE ALSO         top

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

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@groups.io.  This page was obtained from the project's upstream
       Git repository ⟨https://github.com/performancecopilot/pcp.git⟩ on
       2019-09-26.  (At that time, the date of the most recent commit that
       was found in the repository was 2019-09-26.)  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)

Pages that refer to this page: pmrep(1)