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 pcp options -A/--align,
18 -a/--archive, -h/--host, -O/--origin, -S/--start, -s/--samples,
19 -T/--finish, -t/--interval, -v/--version, -Z/--timezone and
20 -z/--hostzone become indirectly available; refer to PCPIntro(1) for a
21 complete description of these options.
22 The additional command line options available for pcp-iostat are:
24 -G method, --aggregate=method
26 Specifies that statistics for device names matching the regular
27 expression specified with the -R regex option should be aggregated
28 according to method. Note this is aggregation based on matching
29 device names (not temporal aggregation). When -G is used, the de‐
30 vice name column is reported as method(regex), e.g. if -G sum -R
31 'sd(a|b)$' is specified, the device column will be sum(sd(a|b)$)
32 and summed statistics for sda and sdb will be reported in the re‐
33 maining columns. If -G is specified but -R is not specified, then
34 the default regex is .*, i.e. matching all device names. If meth‐
35 od is sum then the statistics are summed. This includes the %util
36 column, which may therefore exceed 100% if more than one device
37 name matches. If method is avg then the statistics are summed and
38 then averaged by dividing by the number of matching device names.
39 If method is min or max, the minimum or maximum statistics for
40 matching devices are reported, respectively.
41 -P N, --precision=N
43 This indicates the precision (number of decimal places) to report.
44 The default precision N may be set to something other than the de‐
45 fault (2). Note that the avgrq-sz and avgqu-sz fields are always
46 reported with N+1 decimals of precision. These fields typically
47 have values less than 1.
48 -R pattern, --regex=pattern
50 This restricts the report to device names matching a regular ex‐
51 pression pattern. The given pattern is searched as a perl style
52 regular expression, and will match any portion of a device name.
53 e.g. '^sd[a-zA-Z]+' will match all device names starting with 'sd'
54 followed by one or more alphabetic characters. e.g. '^sd(a|b)$'
55 will only match 'sda' and 'sdb'. e.g. 'sda$' will match 'sda' but
56 not 'sdab'. See also the -G option for aggregation options.
57 -u, --no-interpolation
59 When replaying a set of archives, by default values are reported
60 according to the requested sample interval (-t option), not ac‐
61 cording to the actual interval recorded in the archive(s). With‐
62 out this option PCP interpolates the values to be reported based
63 on the records in the set of archives, which is particularly use‐
64 ful when the -t option is used to replay a set of archives with a
65 longer sampling interval than that with which the archive(s) was
66 originally recorded with. With the -u option, uninterpolated re‐
67 porting is enabled - every value is reported according to the na‐
68 tive recording interval in the set of archives. When the -u op‐
69 tion is specified, the -t option makes no sense and is incompati‐
70 ble because the replay interval is always the same as the record‐
71 ing interval in the set of archive. In addition, -u only makes
72 sense when replaying archives, see the -a option on PCPIntro(1),
73 and so if -u is specified then -a must also be specified.
74 -V, --version
76 Display version number and exit.
77 -x comma-separated-options
79 Specifies a comma-separated list of one or more extended reporting
80 options as follows:
81 dm - report statistics for device-mapper logical devices instead
82 of SCSI devices,
83 t - prefix every line in the report with a timestamp in ctime(3)
84 format,
85 h - omit the heading, which is otherwise reported every 24 sam‐
86 ples,
87 noidle - Do not display statistics for idle devices.
88 -?, --help
90 Display usage message and exit.
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93 The columns in the pcp-iostat report have the following interpretation:
94 Timestamp
96 When the -x t option is specified, this column is the timestamp
97 in ctime(3) format.
98 Device Specifies the scsi device name, or if -x dm is specified, the
100 device-mapper logical device name. When -G is specified, this
101 is replaced by the aggregation method and regular expression -
102 see the -G and -R options above.
103 rrqm/s The number of read requests expressed as a rate per-second that
105 were merged during the reporting interval by the I/O scheduler.
106 wrqm/s The number of write requests expressed as a rate per-second that
108 were merged during the reporting interval by the I/O scheduler.
109 r/s The number of read requests completed by the device (after
111 merges), expressed as a rate per second during the reporting in‐
112 terval.
113 w/s The number of write requests completed by the device (after
115 merges), expressed as a rate per second during the reporting in‐
116 terval.
117 rkB/s The average volume of data read from the device expressed as
119 KBytes/second during the reporting interval.
120 wkB/s The average volume of data written to the device expressed as
122 KBytes/second during the reporting interval.
123 avgrq-sz
125 The average I/O request size for both reads and writes to the
126 device expressed as Kbytes during the reporting interval.
127 avgqu-sz
129 The average queue length of read and write requests to the de‐
130 vice during the reporting interval.
131 await The average time in milliseconds that read and write requests
133 were queued (and serviced) to the device during the reporting
134 interval.
135 r_await
137 The average time in milliseconds that read requests were queued
138 (and serviced) to the device during the reporting interval.
139 w_await
141 The average time in milliseconds that write requests were queued
142 (and serviced) to the device during the reporting interval.
143 %util The percentage of time during the reporting interval that the
145 device was busy processing requests. A value of 100% indicates
146 device saturation.
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149 Environment variables with the prefix PCP_ are used to parameterize the
150 file and directory names used by PCP. On each installation, the file
151 /etc/pcp.conf contains the local values for these variables. The
152 $PCP_CONF variable may be used to specify an alternative configuration
153 file, as described in pcp.conf(5).
154 For environment variables affecting PCP tools, see pmGetOptions(3).
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158 PCPIntro(1), pcp(1), iostat2pcp(1), pmcd(1), pmchart(1), pmlogger(1),
159 pcp.conf(5) and pcp.env(5).
160Performance Co-Pilot PCP PCP-IOSTAT(1)