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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | REPORT | PCP ENVIRONMENT | SEE ALSO | COLOPHON |
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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 pcp options -A/--align,
-a/--archive, -h/--host, -O/--origin, -S/--start, -s/--samples,
-t/--interval, -T/--finish, -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-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.
-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:
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-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).
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 [email protected]. This page was obtained from the
project's upstream Git repository
⟨https://github.com/performancecopilot/pcp.git⟩ on 2024-06-14.
(At that time, the date of the most recent commit that was found
in the repository was 2024-06-14.) 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
[email protected]
Performance Co-Pilot PCP PCP-TAPESTAT(1)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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