'\"macro stdmacro
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.TH PCP-TAPESTAT 1 "PCP" "Performance Co-Pilot"
.SH NAME
\f3pcp-tapestat\f1 \- report tape I/O statistics
.SH SYNOPSIS
\f3pcp\f1 [\f2pcp\ options\f1] \f3tapestat\f1
[\f3\-u?\f1]
[\f3\-G\f1 \f2method\f1]
[\f3\-P\f1 \f2precision\f1]
[\f3\-R\f1 \f2pattern\f1]
[\f3\-x\f1 [t][,h][,noidle]\f1]
.SH DESCRIPTION
.B pcp-tapestat
reports I/O statistics for tape devices.
.SH OPTIONS
When invoked via the
.BR pcp (1)
command, the
.I "pcp options"
.hy 0
.BR \-A /\c
.BR \-\-align ,
.BR \-a /\c
.BR \-\-archive ,
.BR \-h /\c
.BR \-\-host ,
.BR \-O /\c
.BR \-\-origin ,
.BR \-S /\c
.BR \-\-start ,
.BR \-s /\c
.BR \-\-samples ,
.BR \-t /\c
.BR \-\-interval ,
.BR \-T /\c
.BR \-\-finish ,
.BR \-V /\c
.BR \-\-version ,
.BR \-Z /\c
.BR \-\-timezone
and
.BR \-z /\c
.BR \-\-hostzone
become indirectly available; refer to
.BR PCPIntro (1)
for a complete description of these options.
.br
.hy 0
.PP
The additional command line options available for
.B pcp-tapestat
are:
.TP 5
\fB\-G \fImethod\fR\fR, \fB\-\-aggregate\fR=\fImethod\fR
Specifies that statistics for device names matching the regular
expression specified with the
.B \-R
.I regex
option should be aggregated according to
.IR method .
Note this is aggregation based on matching device names (not
temporal aggregation).
When
.B \-G
is used,
the device name column is reported as
.IR method (\fIregex\fR),
e.g.
if
.B \-G sum
.B \-R 'st(0|1)$'
is specified, the device column will be
.BR sum (\fBst(0|1)$)\fR
and
summed statistics for
.B st0
and
.B st1
will be reported in the remaining columns.
If
.B \-G
is specified but
.B \-R
is not specified, then the default
.I regex
is
.BR .* ,
i.e. matching all device names.
If
.I method
is
.B sum
then the statistics are summed.
If
.I method
is
.B avg
then the statistics are summed and then averaged by dividing by the
number of matching device names.
If
.I method
is
.B min
or
.BR max ,
the minimum or maximum statistics for matching devices are reported,
respectively.
.TP
\fB\-P\fR \fIN\fR, \fB\-\-precision\fR=\fIN\fR
This indicates the precision (number of decimal places) to report.
The default precision \f2N\f1
may be set to something other than the default (2).
Note that the
.B avgrq-sz
and
.B avgqu-sz
fields are always reported with \f2N\f1+1 decimals of precision.
These fields typically have values less than 1.
.TP
\fB\-R\fR \fIpattern\fR, \fB\-\-regex\fR=\fIpattern\fR
This restricts the report to device names matching a regular expression
.IR pattern .
The given
.I 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
.B \-G
option for aggregation options.
.TP
\fB\-u\fR, \fB\-\-no-interpolation\fR
When replaying a set of archives, by default values are reported
according to the requested sample interval (\c
.B \-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
.B \-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
.B \-u
option,
uninterpolated reporting is enabled - every value is reported
according to the native recording interval in the set of archives.
When the
.B \-u
option is specified, the
.B \-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,
.B \-u
only makes sense when replaying archives, see the
.B \-a
option on
.BR PCPIntro (1),
and so if
.B \-u
is specified then
.B \-a
must also be specified.
.TP
\fB\-V\fR, \fB\-\-version\fR
Display version number and exit.
.TP
\f3\-x\f1 \f2comma-separated-options\f1
Specifies a comma-separated list of one or more extended reporting
options as follows:
.br
\f3t\fP - prefix every line in the report with a timestamp in
\f2ctime\fP(3) format,
.br
\f3h\fP - omit the heading, which is otherwise reported every 24 samples,
.br
\f3noidle\fP - Do not display statistics for idle devices.
.TP
\fB\-?\fR, \fB\-\-help\fR
Display usage message and exit.
.SH REPORT
The columns in the
.B pcp-tapestat
report have the following interpretation:
.TP
.B Timestamp
When the \f3\-x t\fP option is specified, this column is the timestamp
in \f3ctime\fP(3) format.
.TP
.B Device
Specifies the tape device name.
When
.B \-G
is specified, this is replaced by the aggregation method and regular expression - see the
.B \-G
and
.B \-R
options above.
.TP
.B r/s
The number of reads issued expressed as the number per second averaged
over the interval.
.TP
.B w/s
The number of writes issued expressed as the number per second averaged
over the interval.
.TP
.B kb_r/s
The amount of data read expressed in kilobytes per second averaged
over the interval.
.TP
.B kb_w/s
The amount of data written expressed in kilobytes per second averaged
over the interval.
.TP
.B 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.
.TP
.B 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.
.TP
.B 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).
.TP
.B 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.
.TP
.B 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).
.SH PCP ENVIRONMENT
Environment variables with the prefix \fBPCP_\fP are used to parameterize
the file and directory names used by PCP.
On each installation, the
file \fI/etc/pcp.conf\fP contains the local values for these variables.
The \fB$PCP_CONF\fP variable may be used to specify an alternative
configuration file, as described in \fBpcp.conf\fP(5).
.PP
For environment variables affecting PCP tools, see \fBpmGetOptions\fP(3).
.SH SEE ALSO
.BR PCPIntro (1),
.BR pcp (1),
.BR pmcd (1),
.BR pmchart (1),
.BR pmlogger (1),
.BR pcp.conf (5)
and
.BR pcp.env (5).