1PCP-IOSTAT(1) General Commands Manual PCP-IOSTAT(1)
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6 pmiostat, pcp-iostat - report block I/O statistics
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9 pcp [pcp options] iostat [-u?] [-G method] [-P precision] [-R pattern]
10 [-x [dm][,t][,h][,noidle]]
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13 pcp-iostat reports I/O statistics for SCSI (by default) or other de‐
14 vices (if the -x option is specified).
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17 When invoked via the pcp(1) command, the -a/--archive, -h/--host,
18 -O/--origin, -s/--samples, -t/--interval, -Z/--timezone and several
19 other pcp options become indirectly available; refer to PCPIntro(1) for
20 a complete description of these options.
21 The additional command line options available for pcp-iostat 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 de‐
29 vice name column is reported as method(regex), e.g. if -G sum -R
30 'sd(a|b)$' is specified, the device column will be sum(sd(a|b)$)
31 and summed statistics for sda and sdb will be reported in the re‐
32 maining columns. If -G is specified but -R is not specified, then
33 the default regex is .*, i.e. matching all device names. If
34 method is sum then the statistics are summed. This includes the
35 %util column, which may therefore exceed 100% if more than one de‐
36 vice name matches. If method is avg then the statistics are
37 summed and then averaged by dividing by the number of matching de‐
38 vice names. If method is min or max, the minimum or maximum sta‐
39 tistics for matching devices are reported, respectively.
40 -P N, --precision=N
42 This indicates the precision (number of decimal places) to report.
43 The default precision N may be set to something other than the de‐
44 fault (2). Note that the avgrq-sz and avgqu-sz fields are always
45 reported with N+1 decimals of precision. These fields typically
46 have values less than 1.
47 -R pattern, --regex=pattern
49 This restricts the report to device names matching a regular ex‐
50 pression pattern. The given pattern is searched as a perl style
51 regular expression, and will match any portion of a device name.
52 e.g. '^sd[a-zA-Z]+' will match all device names starting with 'sd'
53 followed by one or more alphabetic characters. e.g. '^sd(a|b)$'
54 will only match 'sda' and 'sdb'. e.g. 'sda$' will match 'sda' but
55 not 'sdab'. See also the -G option for aggregation options.
56 -u, --no-interpolation
58 When replaying a set of archives, by default values are reported
59 according to the requested sample interval (-t option), not ac‐
60 cording to the actual interval recorded in the archive(s). With‐
61 out this option PCP interpolates the values to be reported based
62 on the records in the set of archives, which is particularly use‐
63 ful when the -t option is used to replay a set of archives with a
64 longer sampling interval than that with which the archive(s) was
65 originally recorded with. With the -u option, uninterpolated re‐
66 porting is enabled - every value is reported according to the na‐
67 tive recording interval in the set of archives. When the -u op‐
68 tion is specified, the -t option makes no sense and is incompati‐
69 ble because the replay interval is always the same as the record‐
70 ing interval in the set of archive. In addition, -u only makes
71 sense when replaying archives, see the -a option on PCPIntro(1),
72 and so if -u is specified then -a must also be specified.
73 -x comma-separated-options
75 Specifies a comma-separated list of one or more extended reporting
76 options as follows:
77 dm - report statistics for device-mapper logical devices instead
78 of SCSI devices,
79 t - prefix every line in the report with a timestamp in ctime(3)
80 format,
81 h - omit the heading, which is otherwise reported every 24 sam‐
82 ples,
83 noidle - Do not display statistics for idle devices.
84 -?, --help
86 Display usage message and exit.
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89 The columns in the pcp-iostat report have the following interpretation:
90 Timestamp
92 When the -x t option is specified, this column is the timestamp
93 in ctime(3) format.
94 Device Specifies the scsi device name, or if -x dm is specified, the
96 device-mapper logical device name. When -G is specified, this
97 is replaced by the aggregation method and regular expression -
98 see the -G and -R options above.
99 rrqm/s The number of read requests expressed as a rate per-second that
101 were merged during the reporting interval by the I/O scheduler.
102 wrqm/s The number of write requests expressed as a rate per-second that
104 were merged during the reporting interval by the I/O scheduler.
105 r/s The number of read requests completed by the device (after
107 merges), expressed as a rate per second during the reporting in‐
108 terval.
109 w/s The number of write requests completed by the device (after
111 merges), expressed as a rate per second during the reporting in‐
112 terval.
113 rkB/s The average volume of data read from the device expressed as
115 KBytes/second during the reporting interval.
116 wkB/s The average volume of data written to the device expressed as
118 KBytes/second during the reporting interval.
119 avgrq-sz
121 The average I/O request size for both reads and writes to the
122 device expressed as Kbytes during the reporting interval.
123 avgqu-sz
125 The average queue length of read and write requests to the de‐
126 vice during the reporting interval.
127 await The average time in milliseconds that read and write requests
129 were queued (and serviced) to the device during the reporting
130 interval.
131 r_await
133 The average time in milliseconds that read requests were queued
134 (and serviced) to the device during the reporting interval.
135 w_await
137 The average time in milliseconds that write requests were queued
138 (and serviced) to the device during the reporting interval.
139 %util The percentage of time during the reporting interval that the
141 device was busy processing requests. A value of 100% indicates
142 device saturation.
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145 Environment variables with the prefix PCP_ are used to parameterize the
146 file and directory names used by PCP. On each installation, the file
147 /etc/pcp.conf contains the local values for these variables. The
148 $PCP_CONF variable may be used to specify an alternative configuration
149 file, as described in pcp.conf(5).
150 For environment variables affecting PCP tools, see pmGetOptions(3).
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154 PCPIntro(1), pcp(1), iostat2pcp(1), pmcd(1), pmchart(1), pmlogger(1),
155 pcp.conf(5) and pcp.env(5).
156Performance Co-Pilot PCP PCP-IOSTAT(1)