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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | REPORT | DIAGNOSTICS | PCP ENVIRONMENT | SEE ALSO | COLOPHON |
PCP-TAPESTAT(1) General Commands Manual PCP-TAPESTAT(1)
pcp-tapestat - report tape I/O statistics
pcp [pcp options] tapestat [-u] [-G method] [-P precision] [-R
pattern] [-x [t][,h][,noidle]]
pcp-tapestat reports I/O statistics for tape devices.
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-tapestat 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 'st(0|1)$' is specified, the device column will be
sum(st(0|1)$) and summed statistics for st0 and st1 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.
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. '^st[0-9]+' will match all device names starting
with 'st' followed by one or more numbers. e.g. '^st(0|1)$'
will only match 'st0' and 'st1'. e.g. 'st0$' will match 'st0'
but not 'st1'. 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:
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-tapestat 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 tape device name. When -G is specified, this is
replaced by the aggregation method and regular expression -
see the -G and -R options above.
r/s The number of reads issued expressed as the number per second
averaged over the interval.
w/s The number of writes issued expressed as the number per second
averaged over the interval.
kb_r/s The amount of data read expressed in kilobytes per second
averaged over the interval.
kb_w/s The amount of data written expressed in kilobytes per second
averaged over the interval.
r_pct Read percentage wait - the percentage of time over the
interval spent waiting for read requests to complete. The
time is measured from when the request is dispatched to the
SCSI mid-layer until it signals that it completed.
w_pct Write percentage wait - the percentage of time over the
interval spent waiting for write requests to complete. The
time is measured from when the request is dispatched to the
SCSI mid-layer until it signals that it completed.
o_pct Overall percentage wait - the percentage of time over the
interval spent waiting for any I/O request to complete (read,
write, and other).
Rs/s The number of I/Os, expressed as the number per second
averaged over the interval, where a non-zero residual value
was encountered.
o_cnt The number of I/Os, expressed as the number per second
averaged over the interval, that were included as "other".
Other I/O includes ioctl calls made to the tape driver and
implicit operations performed by the tape driver such as
rewind on close (for tape devices that implement rewind on
close). It does not include any I/O performed using methods
outside of the tape driver (e.g. via sg ioctls).
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), 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-TAPESTAT(1)