'\" t
'\"macro stdmacro
.\"
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.\" 
.\" This program is free software; you can redistribute it and/or modify it
.\" under the terms of the GNU General Public License as published by the
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.\"
.TH PMIOSTAT 1 "PCP" "Performance Co-Pilot"
.SH NAME
\f3pmiostat\f1 \- performance metrics value dumper
.\" literals use .B or \f3
.\" arguments use .I or \f2
.SH SYNOPSIS
\f3pmiostat\f1
[\f3\-A\f1 \f2align\f1 \f3--align=\f2TIME\f1]
[\f3\-a\f1 \f2archive\f1 \f3--archive=\f2FILE\f1]
[\f3\-h\f1 \f2host\f1 \f3--host=\f2HOST\f1]
[\f3\-O\f1 \f2offset\f1 \f3--origin=\f2TIME\f1]
[\f3\-S\f1 \f2starttime\f1 \f3--start=\f2TIME\f1]
[\f3\-s\f1 \f2samples\f1 \f3--samples=\f2N\f1]
[\f3\-T\f1 \f2endtime\f1 \f3--finish=\f2TIME\f1]
[\f3\-t\f1 \f2interval\f1 \f3--interval=\f2DELTA\f1]
[\f3\-Z\f1 \f2timezone\f1 \f3--timezone=\f2TZ\f1]
[\f3\-z\f1 \f3--hostzone\f1]
[\f3\-?\f1 \f3--help\f1]
[\f3\-x\f1 [dm][,t][,h]\f1]
.SH DESCRIPTION
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..
.B pmiostat
reports I/O statistics for scsi devices (by default) or device-mapper devices (if the \f3-x dm\f1 option is specified).
By default
.B pmiostat
reports live data for the local host but can also report for a remote host (\f3-h\fP) or from a previously captured PCP archive (\f3-a\fP).
.PP
The
.BR \-S ,
.BR \-T ,
.BR \-O
and
.B \-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
.BR PCPIntro (1)
for a complete description of these options.
.PP
The other options which control the source, timing and layout of the information
reported by
.B pmiostat
are as follows:
.TP 5
.B \-a
Performance metric values are retrieved from the Performance Co-Pilot (PCP)
archive log file identified by the base name
.IR archive .
.TP
.B \-h
Current performance metric values are retrieved from the nominated
.I host
machine.
.TP
.B \-s
The argument
.I samples
defines the number of samples to be retrieved and reported.
If
.I samples
is 0 or
.B \-s
is not specified, 
.B pmiostat
will sample and report continuously (in real time mode) or until the end
of the PCP archive (in archive mode).
.TP
.B \-t
The default update \f2interval\f1 may be set to something other than the
default 1 second.
The
.I interval
argument follows the syntax described in
.BR PCPIntro (1),
and in the simplest form may be an unsigned integer (the implied
units in this case are seconds).
The \f3-t\fP option is particularly useful when replaying large archives (\f3-a\fP option) that span several hours or even days.
In this case specifying a large
.I 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.
.TP
.B \-Z
By default,
.B pmiostat
reports the time of day according to the local timezone on the
system where
.B pmiostat
is run.
The
.B \-Z
option changes the timezone to
.I timezone
in the format of the environment variable
.B TZ
as described in
.BR environ (5).
.TP
.B \-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
.B \-h
or
.B \-a
options.
.TP
.B \-x
Specifies a comma separated list of one or more extended reporting options as follows:
.br
\f3dm\fP - report statistics for device-mapper logical devices instead of scsi devices,
.br
\f3t\fP - prefix every line in the report with a timestamp in \f2ctime\fP(3) format,
.br
\f3H\fP - omit the heading, which is otherwise reported every 24 samples.
.SH REPORT
The columns in the
.B pmiostat
report have the following interpretation :
.TP
.B Timestamp
When the \f3-x t\fP option is specified, this column is the timestamp in \f3ctime\fP(3) format.
.TP
.B Device
Specifies the scsi device name, or if \f3-x dm\fP is specified, the device-mapper logical device name.
.TP
.B 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.
.TP
.B 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.
.TP
.B r/s
The number of read requests completed by the device (after merges), expressed as a rate per second during the reporting interval.
.TP
.B w/s
The number of write requests completed by the device (after merges), expressed as a rate per second during the reporting interval.
.TP
.B rkB/s
The average volume of data read from the device expressed as KBytes/second during the reporting interval.
.TP
.B wkB/s
The average volume of data written to the device expressed as KBytes/second during the reporting interval.
.TP
.B avgrq-sz
The average I/O request size for both reads and writes to the device expressed as Kbytes during the reporting interval.
.TP
.B avgqu-sz
The average queue length of read and write requests to the device during the reporting interval.
.TP
.B await
The average time in milliseconds that read and write requests were queued (and serviced) to the device during the reporting interval.
.TP
.B r_await
The average time in milliseconds that read requests were queued (and serviced) to the device during the reporting interval.
.TP
.B w_await
The average time in milliseconds that write requests were queued (and serviced) to the device during the reporting interval.
.TP
.B %util
The percentage of time during the reporting interval that the device was busy processing requests.
A value of 100% indicates device saturation.
.SH FILES
.PD 0
.TP 10
.BI $PCP_VAR_DIR/pmns/ *
default PMNS specification files
.PD
.SH "PCP ENVIRONMENT"
Environment variables with the prefix
.B PCP_
are used to parameterize the file and directory names
used by PCP.
On each installation, the file
.I /etc/pcp.conf
contains the local values for these variables.
The
.B $PCP_CONF
variable may be used to specify an alternative
configuration file,
as described in
.BR pcp.conf (5).
.SH SEE ALSO
.BR PCPIntro (1),
.BR pmcd (1),
.BR pmchart (1),
.BR pmdumplog (1),
.BR pminfo (1),
.BR pmlogger (1),
.BR pmtime (1),
.BR PMAPI (3),
.BR __pmSpecLocalPMDA (3),
.BR pcp.conf (5)
and
.BR pcp.env (5).
.SH DIAGNOSTICS
All are generated on standard error and are intended to be self-explanatory.