1PCP-TAPESTAT(1) General Commands Manual PCP-TAPESTAT(1)
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6 pcp-tapestat - report tape I/O statistics
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9 pcp [pcp options] tapestat [-u?] [-G method] [-P precision] [-R pat‐
10 tern] [-x [t][,h][,noidle]]
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13 pcp-tapestat reports I/O statistics for tape devices.
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16 When invoked via the pcp(1) command, the pcp options -A/--align,
17 -a/--archive, -h/--host, -O/--origin, -S/--start, -s/--samples,
18 -t/--interval, -T/--finish, -V/--version, -Z/--timezone and
19 -z/--hostzone become indirectly available; refer to PCPIntro(1) for a
20 complete description of these options.
21 The additional command line options available for pcp-tapestat are:
23 -G method, --aggregate=method
25 Specifies that statistics for device names matching the regular
26 expression specified with the -R regex option should be aggregated
27 according to method. Note this is aggregation based on matching
28 device names (not temporal aggregation). When -G is used, the
29 device name column is reported as method(regex), e.g. if -G sum
30 -R 'st(0|1)$' is specified, the device column will be
31 sum(st(0|1)$) and summed statistics for st0 and st1 will be
32 reported in the remaining columns. If -G is specified but -R is
33 not specified, then the default regex is .*, i.e. matching all
34 device names. If method is sum then the statistics are summed.
35 If method is avg then the statistics are summed and then averaged
36 by dividing by the number of matching device names. If method is
37 min or max, the minimum or maximum statistics for matching devices
38 are reported, respectively.
39 -P N, --precision=N
41 This indicates the precision (number of decimal places) to report.
42 The default precision N may be set to something other than the
43 default (2). Note that the avgrq-sz and avgqu-sz fields are
44 always reported with N+1 decimals of precision. These fields
45 typically have values less than 1.
46 -R pattern, --regex=pattern
48 This restricts the report to device names matching a regular
49 expression pattern. The given pattern is searched as a perl style
50 regular expression, and will match any portion of a device name.
51 e.g. '^st[0-9]+' will match all device names starting with 'st'
52 followed by one or more numbers. e.g. '^st(0|1)$' will only match
53 'st0' and 'st1'. e.g. 'st0$' will match 'st0' but not 'st1'. See
54 also the -G option for aggregation options.
55 -u, --no-interpolation
57 When replaying a set of archives, by default values are reported
58 according to the requested sample interval (-t option), not
59 according to the actual interval recorded in the archive(s).
60 Without this option PCP interpolates the values to be reported
61 based on the records in the set of archives, which is particularly
62 useful when the -t option is used to replay a set of archives with
63 a longer sampling interval than that with which the archive(s) was
64 originally recorded with. With the -u option, uninterpolated
65 reporting is enabled - every value is reported according to the
66 native recording interval in the set of archives. When the -u
67 option is specified, the -t option makes no sense and is
68 incompatible because the replay interval is always the same as the
69 recording interval in the set of archive. In addition, -u only
70 makes sense when replaying archives, see the -a option on
71 PCPIntro(1), and so if -u is specified then -a must also be
72 specified.
73 -V, --version
75 Display version number and exit.
76 -x comma-separated-options
78 Specifies a comma-separated list of one or more extended reporting
79 options as follows:
80 t - prefix every line in the report with a timestamp in ctime(3)
81 format,
82 h - omit the heading, which is otherwise reported every 24
83 samples,
84 noidle - Do not display statistics for idle devices.
85 -?, --help
87 Display usage message and exit.
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90 The columns in the pcp-tapestat report have the following
91 interpretation:
92 Timestamp
94 When the -x t option is specified, this column is the timestamp
95 in ctime(3) format.
96 Device Specifies the tape device name. When -G is specified, this is
98 replaced by the aggregation method and regular expression - see
99 the -G and -R options above.
100 r/s The number of reads issued expressed as the number per second
102 averaged over the interval.
103 w/s The number of writes issued expressed as the number per second
105 averaged over the interval.
106 kb_r/s The amount of data read expressed in kilobytes per second
108 averaged over the interval.
109 kb_w/s The amount of data written expressed in kilobytes per second
111 averaged over the interval.
112 r_pct Read percentage wait - the percentage of time over the interval
114 spent waiting for read requests to complete. The time is
115 measured from when the request is dispatched to the SCSI mid-
116 layer until it signals that it completed.
117 w_pct Write percentage wait - the percentage of time over the interval
119 spent waiting for write requests to complete. The time is
120 measured from when the request is dispatched to the SCSI mid-
121 layer until it signals that it completed.
122 o_pct Overall percentage wait - the percentage of time over the
124 interval spent waiting for any I/O request to complete (read,
125 write, and other).
126 Rs/s The number of I/Os, expressed as the number per second averaged
128 over the interval, where a non-zero residual value was
129 encountered.
130 o_cnt The number of I/Os, expressed as the number per second averaged
132 over the interval, that were included as "other". Other I/O
133 includes ioctl calls made to the tape driver and implicit
134 operations performed by the tape driver such as rewind on close
135 (for tape devices that implement rewind on close). It does not
136 include any I/O performed using methods outside of the tape
137 driver (e.g. via sg ioctls).
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140 Environment variables with the prefix PCP_ are used to parameterize the
141 file and directory names used by PCP. On each installation, the file
142 /etc/pcp.conf contains the local values for these variables. The
143 $PCP_CONF variable may be used to specify an alternative configuration
144 file, as described in pcp.conf(5).
145 For environment variables affecting PCP tools, see pmGetOptions(3).
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149 PCPIntro(1), pcp(1), pmcd(1), pmchart(1), pmlogger(1), pcp.conf(5) and
150 pcp.env(5).
151Performance Co-Pilot PCP PCP-TAPESTAT(1)