SYNOPSISpmiostat [-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]]
DESCRIPTIONpmiostat reports I/O statistics for scsi devices (by default) or device-mapper devices (if the -x dm option is specified). By default pmiostat 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 pmiostat are as follows:
- Performance metric values are retrieved from the Performance Co-Pilot (PCP) archive log file identified by the base name archive.
- Current performance metric values are retrieved from the nominated host machine.
- The argument samples defines the number of samples to be retrieved and reported. If samples is 0 or -s is not specified, pmiostat will sample and report continuously (in real time mode) or until the end of the PCP archive (in archive mode).
- 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.
- By default, pmiostat reports the time of day according to the local timezone on the system where pmiostat is run. The -Z option changes the timezone to timezone in the format of the environment variable TZ as described in environ(5).
- 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.
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.
REPORTThe columns in the pmiostat report have the following interpretation :
- When the -x t option is specified, this column is the timestamp in ctime(3) format.
- Specifies the scsi device name, or if -x dm is specified, the device-mapper logical device name.
- The number of read requests expressed as a rate per-second that were merged during the reporting interval by the I/O scheduler.
- The number of write requests expressed as a rate per-second that were merged during the reporting interval by the I/O scheduler.
- The number of read requests completed by the device (after merges), expressed as a rate per second during the reporting interval.
- The number of write requests completed by the device (after merges), expressed as a rate per second during the reporting interval.
- The average volume of data read from the device expressed as KBytes/second during the reporting interval.
- The average volume of data written to the device expressed as KBytes/second during the reporting interval.
- The average I/O request size for both reads and writes to the device expressed as Kbytes during the reporting interval.
- The average queue length of read and write requests to the device during the reporting interval.
- The average time in milliseconds that read and write requests were queued (and serviced) to the device during the reporting interval.
- The average time in milliseconds that read requests were queued (and serviced) to the device during the reporting interval.
- The average time in milliseconds that write requests were queued (and serviced) to the device during the reporting interval.
- The percentage of time during the reporting interval that the device was busy processing requests. A value of 100% indicates device saturation.
- default PMNS specification files
PCP ENVIRONMENTEnvironment 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).
DIAGNOSTICSAll are generated on standard error and are intended to be self-explanatory.