Provided by: pcp_4.3.1-1_amd64 bug

NAME

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

SYNOPSIS

       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

       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

       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

       $PCP_VAR_DIR/pmns/*
                 default PMNS specification files

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

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

DIAGNOSTICS

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