NAME

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

SYNOPSIS

       pcp iostat  [-A  align --align=TIME] [-a archive --archive=FILE] [-h host --host=HOST] [-O
       offset --origin=TIME] [-S starttime --start=TIME] [-s  samples  --samples=N]  [-T  endtime
       --finish=TIME]  [-t interval --interval=DELTA] [-Z timezone --timezone=TZ] [-z --hostzone]
       [-? --help] [-x [dm][,t][,h]]

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 file identified by the base name archive.

       -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 PCP archive (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 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.

       -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.

       -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.

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.

       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.