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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | REPORT | DIAGNOSTICS | PCP ENVIRONMENT | SEE ALSO | COLOPHON |
PCP-IOSTAT(1) General Commands Manual PCP-IOSTAT(1)
pmiostat, pcp-iostat - report block I/O statistics
pcp [pcp options] iostat [-u] [-G method] [-P precision] [-R pattern]
[-x [dm][,t][,h][,noidle]]
pcp-iostat reports I/O statistics for SCSI (by default) or other
devices (if the -x option is specified).
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.
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.
All are generated on standard error and are intended to be self-
explanatory.
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).
PCPIntro(1), pcp(1), iostat2pcp(1), pmcd(1), pmchart(1), pmlogger(1),
pcp.conf(5) and pcp.env(5).
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
2020-08-13. (At that time, the date of the most recent commit that
was found in the repository was 2020-08-11.) 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: pcp2csv(1) , pmrep(1)