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 -a/--archive, -h/--host,
17 -O/--origin, -s/--samples, -t/--interval, -Z/--timezone and several
18 other pcp options become indirectly available; refer to PCPIntro(1) for
19 a complete description of these options.
20 The additional command line options available for pcp-tapestat are:
22 -G method, --aggregate=method
24 Specifies that statistics for device names matching the regular
25 expression specified with the -R regex option should be aggregated
26 according to method. Note this is aggregation based on matching
27 device names (not temporal aggregation). When -G is used, the de‐
28 vice name column is reported as method(regex), e.g. if -G sum -R
29 'st(0|1)$' is specified, the device column will be sum(st(0|1)$)
30 and summed statistics for st0 and st1 will be reported in the re‐
31 maining columns. If -G is specified but -R is not specified, then
32 the default regex is .*, i.e. matching all device names. If
33 method is sum then the statistics are summed. If method is avg
34 then the statistics are summed and then averaged by dividing by
35 the number of matching device names. If method is min or max, the
36 minimum or maximum statistics for matching devices are reported,
37 respectively.
38 -P N, --precision=N
40 This indicates the precision (number of decimal places) to report.
41 The default precision N may be set to something other than the de‐
42 fault (2). Note that the avgrq-sz and avgqu-sz fields are always
43 reported with N+1 decimals of precision. These fields typically
44 have values less than 1.
45 -R pattern, --regex=pattern
47 This restricts the report to device names matching a regular ex‐
48 pression pattern. The given pattern is searched as a perl style
49 regular expression, and will match any portion of a device name.
50 e.g. '^st[0-9]+' will match all device names starting with 'st'
51 followed by one or more numbers. e.g. '^st(0|1)$' will only match
52 'st0' and 'st1'. e.g. 'st0$' will match 'st0' but not 'st1'. See
53 also the -G option for aggregation options.
54 -u, --no-interpolation
56 When replaying a set of archives, by default values are reported
57 according to the requested sample interval (-t option), not ac‐
58 cording to the actual interval recorded in the archive(s). With‐
59 out this option PCP interpolates the values to be reported based
60 on the records in the set of archives, which is particularly use‐
61 ful when the -t option is used to replay a set of archives with a
62 longer sampling interval than that with which the archive(s) was
63 originally recorded with. With the -u option, uninterpolated re‐
64 porting is enabled - every value is reported according to the na‐
65 tive recording interval in the set of archives. When the -u op‐
66 tion is specified, the -t option makes no sense and is incompati‐
67 ble because the replay interval is always the same as the record‐
68 ing interval in the set of archive. In addition, -u only makes
69 sense when replaying archives, see the -a option on PCPIntro(1),
70 and so if -u is specified then -a must also be specified.
71 -x comma-separated-options
73 Specifies a comma-separated list of one or more extended reporting
74 options as follows:
75 t - prefix every line in the report with a timestamp in ctime(3)
76 format,
77 h - omit the heading, which is otherwise reported every 24 sam‐
78 ples,
79 noidle - Do not display statistics for idle devices.
80 -?, --help
82 Display usage message and exit.
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85 The columns in the pcp-tapestat report have the following interpreta‐
86 tion:
87 Timestamp
89 When the -x t option is specified, this column is the timestamp
90 in ctime(3) format.
91 Device Specifies the tape device name. When -G is specified, this is
93 replaced by the aggregation method and regular expression - see
94 the -G and -R options above.
95 r/s The number of reads issued expressed as the number per second
97 averaged over the interval.
98 w/s The number of writes issued expressed as the number per second
100 averaged over the interval.
101 kb_r/s The amount of data read expressed in kilobytes per second aver‐
103 aged over the interval.
104 kb_w/s The amount of data written expressed in kilobytes per second av‐
106 eraged over the interval.
107 r_pct Read percentage wait - the percentage of time over the interval
109 spent waiting for read requests to complete. The time is mea‐
110 sured from when the request is dispatched to the SCSI mid-layer
111 until it signals that it completed.
112 w_pct Write percentage wait - the percentage of time over the interval
114 spent waiting for write requests to complete. The time is mea‐
115 sured from when the request is dispatched to the SCSI mid-layer
116 until it signals that it completed.
117 o_pct Overall percentage wait - the percentage of time over the inter‐
119 val spent waiting for any I/O request to complete (read, write,
120 and other).
121 Rs/s The number of I/Os, expressed as the number per second averaged
123 over the interval, where a non-zero residual value was encoun‐
124 tered.
125 o_cnt The number of I/Os, expressed as the number per second averaged
127 over the interval, that were included as "other". Other I/O in‐
128 cludes ioctl calls made to the tape driver and implicit opera‐
129 tions performed by the tape driver such as rewind on close (for
130 tape devices that implement rewind on close). It does not in‐
131 clude any I/O performed using methods outside of the tape driver
132 (e.g. via sg ioctls).
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135 Environment variables with the prefix PCP_ are used to parameterize the
136 file and directory names used by PCP. On each installation, the file
137 /etc/pcp.conf contains the local values for these variables. The
138 $PCP_CONF variable may be used to specify an alternative configuration
139 file, as described in pcp.conf(5).
140 For environment variables affecting PCP tools, see pmGetOptions(3).
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144 PCPIntro(1), pcp(1), pmcd(1), pmchart(1), pmlogger(1), pcp.conf(5) and
145 pcp.env(5).
146Performance Co-Pilot PCP PCP-TAPESTAT(1)