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
pcp options
-A/
--align,
-a/
--archive,
-h/
--host,
-O/
--origin,
-S/
--start,
-s/
--samples,
-T/
--finish,
-t/
--interval,
-v/
--version,
-Z/
--timezone and
-z/
--hostzone 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.
-
-V, --version
- Display version number and exit.
-
-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.
-
-?, --help
- Display usage message and exit.
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.
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).