pcp-iostat(1) — Linux manual page

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).

OPTIONS         top

       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.

       The additional command line options available for pcp-iostat are:

       -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

       PCPIntro(1), pcp(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 2021-04-01.
       (At that time, the date of the most recent commit that was found
       in the repository was 2021-04-01.)  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)