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NAME | SYNOPSIS | DESCRIPTION | REPORT | FILES | PCP ENVIRONMENT | SEE ALSO | DIAGNOSTICS | COLOPHON |
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PCP-IOSTAT(1) General Commands Manual PCP-IOSTAT(1)
pmiostat, pcp-iostat - performance metrics i/o statistics tool
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]]
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.
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.
$PCP_VAR_DIR/pmns/*
default PMNS specification files
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).
pcp(1), PCPIntro(1), iostat2pcp(1), pmcd(1), pmchart(1), pmlogger(1),
pcp.conf(5) and pcp.env(5).
All are generated on standard error and are intended to be self-
explanatory.
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
2018-02-02. (At that time, the date of the most recent commit that
was found in the repository was 2018-02-02.) 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)
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