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 pattern]
10 [-x [t][,h][,noidle]]
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13 pcp-tapestat reports I/O statistics for tape devices.
14 When invoked via the pcp(1) command, the -a/--archive, -h/--host,
16 -O/--origin, -s/--samples, -t/--interval, -Z/--timezone and several
17 other pcp options become indirectly available; refer to PCPIntro(1) for
18 a complete description of these options.
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21 The options which control the timing and layout of the information
22 reported by pcp-tapestat are as follows:
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 typ‐
45 ically 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 incompat‐
68 ible because the replay interval is always the same as the record‐
69 ing interval in the set of archive. In addition, -u only makes
70 sense when replaying archives, see the -a option on PCPIntro(1),
71 and so if -u is specified then -a must also be specified.
72 -x comma-separated-options
74 Specifies a comma-separated list of one or more extended reporting
75 options as follows:
76 t - prefix every line in the report with a timestamp in ctime(3)
77 format,
78 h - omit the heading, which is otherwise reported every 24 sam‐
79 ples,
80 noidle - Do not display statistics for idle devices.
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83 The columns in the pcp-tapestat report have the following interpreta‐
84 tion:
85 Timestamp
87 When the -x t option is specified, this column is the timestamp
88 in ctime(3) format.
89 Device Specifies the tape device name. When -G is specified, this is
91 replaced by the aggregation method and regular expression - see
92 the -G and -R options above.
93 r/s The number of reads issued expressed as the number per second
95 averaged over the interval.
96 w/s The number of writes issued expressed as the number per second
98 averaged over the interval.
99 kb_r/s The amount of data read expressed in kilobytes per second aver‐
101 aged over the interval.
102 kb_w/s The amount of data written expressed in kilobytes per second
104 averaged over the interval.
105 r_pct Read percentage wait - the percentage of time over the interval
107 spent waiting for read requests to complete. The time is mea‐
108 sured from when the request is dispatched to the SCSI mid-layer
109 until it signals that it completed.
110 w_pct Write percentage wait - the percentage of time over the interval
112 spent waiting for write requests to complete. The time is mea‐
113 sured from when the request is dispatched to the SCSI mid-layer
114 until it signals that it completed.
115 o_pct Overall percentage wait - the percentage of time over the inter‐
117 val spent waiting for any I/O request to complete (read, write,
118 and other).
119 Rs/s The number of I/Os, expressed as the number per second averaged
121 over the interval, where a non-zero residual value was encoun‐
122 tered.
123 o_cnt The number of I/Os, expressed as the number per second averaged
125 over the interval, that were included as "other". Other I/O
126 includes ioctl calls made to the tape driver and implicit opera‐
127 tions performed by the tape driver such as rewind on close (for
128 tape devices that implement rewind on close). It does not
129 include any I/O performed using methods outside of the tape
130 driver (e.g. via sg ioctls).
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133 All are generated on standard error and are intended to be self-
134 explanatory.
135
137 Environment variables with the prefix PCP_ are used to parameterize the
138 file and directory names used by PCP. On each installation, the file
139 /etc/pcp.conf contains the local values for these variables. The
140 $PCP_CONF variable may be used to specify an alternative configuration
141 file, as described in pcp.conf(5).
142 For environment variables affecting PCP tools, see pmGetOptions(3).
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146 pcp(1), PCPIntro(1), pmcd(1), pmchart(1), pmlogger(1), pcp.conf(5) and
147 pcp.env(5).
148Performance Co-Pilot PCP PCP-TAPESTAT(1)