1PMLOGEXTRACT(1) General Commands Manual PMLOGEXTRACT(1)
2
6 pmlogextract - reduce, extract, concatenate and merge Performance Co-
7 Pilot archives
8
10 pmlogextract [-dfmwxz?] [-c configfile] [-S starttime] [-s samples]
11 [-T endtime] [-v volsamples] [-Z timezone] input [...] output
12
14 pmlogextract reads one or more Performance Co-Pilot (PCP) archive logs
15 identified by input and creates a temporally merged and/or reduced PCP
16 archive log in output. input is a comma-separated list of names, each
17 of which may be the base name of an archive or the name of a directory
18 containing one or more archives. The nature of merging is controlled
19 by the number of input archive logs, while the nature of data reduction
20 is controlled by the command line arguments. The input(s) must be sets
21 of PCP archive logs created by pmlogger(1) with performance data col‐
22 lected from the same host, but usually over different time periods and
23 possibly (although not usually) with different performance metrics
24 being logged.
25 If only one input is specified, then the default behavior simply copies
27 the input set of PCP archive logs, into the output PCP archive log.
28 When two or more sets of PCP archive logs are specified as input, the
29 sets of logs are merged (or concatenated) and written to output.
30 In the output archive log a <mark> record may be inserted at a time
32 just past the end of each of the input archive logs to indicate a pos‐
33 sible temporal discontinuity between the end of one input archive log
34 and the start of the next input archive log. See the MARK RECORDS sec‐
35 tion below for more information. There is no <mark> record after the
36 end of the last (in temporal order) of the input archive logs.
37
39 The available command line options are:
40 -c config, --config=config
42 Extract only the metrics specified in config from the input PCP
43 archive log(s). The config syntax accepted by pmlogextract is
44 explained in more detail in the Configuration File Syntax section.
45 -d, --desperate
47 Desperate mode. Normally if a fatal error occurs, all trace of
48 the partially written PCP archive output is removed. With the -d
49 option, the output archive log is not removed.
50 -f, --first
52 For most common uses, all of the input archive logs will have been
53 collected in the same timezone. But if this is not the case, then
54 pmlogextract must choose one of the timezones from the input ar‐
55 chive logs to be used as the timezone for the output archive log.
56 The default is to use the timezone from the last input archive
57 log. The -f option forces the timezone from the first input ar‐
58 chive log to be used.
59 -m, --mark
61 As described in the MARK RECORDS section below, sometimes it is
62 possible to safely omit <mark> records from the output archive.
63 If the -m option is specified, then the epilogue and prologue test
64 is skipped and a <mark> record will always be inserted at the end
65 of each input archive (except the last). This is the original be‐
66 haviour for pmlogextract.
67 -S starttime, --start=starttime
69 Define the start of a time window to restrict the samples
70 retrieved or specify a ``natural'' alignment of the output sample
71 times; refer to PCPIntro(1). See also the -w option.
72 -s samples, --samples=samples
74 The argument samples defines the number of samples to be written
75 to output. If samples is 0 or -s is not specified, pmlogextract
76 will sample until the end of the PCP archive log, or the end of
77 the time window as specified by -T, whichever comes first. The -s
78 option will override the -T option if it occurs sooner.
79 -T endtime, --finish=endtime
81 Define the termination of a time window to restrict the samples
82 retrieved or specify a ``natural'' alignment of the output sample
83 times; refer to PCPIntro(1). See also the -w option.
84 -v volsamples
86 The output archive log is potentially a multi-volume data set, and
87 the -v option causes pmlogextract to start a new volume after vol‐
88 samples log records have been written to the archive log.
89 Independent of any -v option, each volume of an archive is limited
91 to no more than 2^31 bytes, so pmlogextract will automatically
92 create a new volume for the archive before this limit is reached.
93 -w Where -S and -T specify a time window within the same day, the -w
95 flag will cause the data within the time window to be extracted,
96 for every day in the archive log. For example, the options -w -S
97 @11:00 -T @15:00 specify that pmlogextract should include archive
98 log records only for the periods from 11am to 3pm on each day.
99 When -w is used, the output archive log will contain <mark>
100 records to indicate the temporal discontinuity between the end of
101 one time window and the start of the next.
102 -x It is expected that the metadata (name, PMID, type, semantics and
104 units) for each metric will be consistent across all of the input
105 PCP archive log(s) in which that metric appears. In rare cases,
106 e.g. in development, in QA and when a PMDA is upgraded, this may
107 not be the case and pmlogextract will report the issue and abort
108 without creating the output archive log. This is done so the
109 problem can be fixed with pmlogrewrite(1) before retrying the
110 merge. In unattended or QA environments it may be preferable to
111 force the merge and omit the metrics with the mismatched metadata.
112 The -x option does this.
113 -Z timezone, --timezone=timezone
115 Use timezone when displaying the date and time. Timezone is in
116 the format of the environment variable TZ as described in envi‐
117 ron(7). The default is to initially use the timezone of the local
118 host.
119 -z Use the local timezone of the host from the input archive logs.
121 The default is to initially use the timezone of the local host.
122 -? Display usage message and exit.
124
126 The configfile contains metrics of interest - only those metrics (or
127 instances) mentioned explicitly or implicitly in the configuration file
128 will be included in the output archive. Each specifications must begin
129 on a new line, and may span multiple lines in the configuration file.
130 Instances may also be specified, but they are optional. The format for
131 each specification is
132 metric [[instance[,instance...]]]
134 where metric may be a leaf or a non-leaf name in the Performance Met‐
136 rics Name Space (PMNS, see PMNS(5)). If a metric refers to a non-leaf
137 node in the PMNS, pmlogextract will recursively descend the PMNS and
138 include all metrics corresponding to descendent leaf nodes.
139 Instances are optional, and may be specified as a list of one or more
141 space (or comma) separated names, numbers or strings (enclosed in sin‐
142 gle or double quotes). Elements in the list that are numbers are
143 assumed to be internal instance identifiers - see pmGetInDom(3) for
144 more information. If no instances are given, then all instances of the
145 associated metric(s) will be extracted.
146 Any additional white space is ignored and comments may be added with a
148 `#' prefix.
149
151 This is an example of a valid configfile:
152 #
154 # config file for pmlogextract
155 #
156 kernel.all.cpu
158 kernel.percpu.cpu.sys ["cpu0","cpu1"]
159 disk.dev ["dks0d1"]
160
162 When more than one input archive log contributes performance data to
163 the output archive log, then <mark> records may be inserted to indicate
164 a possible discontinuity in the performance data.
165 A <mark> record contains a timestamp and no performance data and is
167 used to indicate that there is a time period in the PCP archive log
168 where we do not know the values of any performance metrics, because
169 there was no pmlogger(1) collecting performance data during this
170 period. Since these periods are often associated with the restart of a
171 service or pmcd(1) or a system, there may be considerable doubt as to
172 the continuity of performance data across this time period.
173 Most current archives are created with a prologue record at the begin‐
175 ning and an epilogue record at the end. These records identify the
176 state of pmcd(1) at the time, and may be used by pmlogextract to deter‐
177 mine that there is no discontinuity between the end of one archive and
178 the next output record, and as a consequence the <mark> record can
179 safely be omitted from the output archive.
180 The rationale behind <mark> records may be demonstrated with an exam‐
182 ple. Consider one input archive log that starts at 00:10 and ends at
183 09:15 on the same day, and another input archive log that starts at
184 09:20 on the same day and ends at 00:10 the following morning. This
185 would be a very common case for archives managed and rotated by pmlog‐
186 ger_check(1) and pmlogger_daily(1).
187 The output archive log created by pmlogextract would contain:
189 00:10.000 first record from first input archive log
190 ...
191 09:15.000 last record from first input archive log
192 09:15.001 <mark> record
193 09:20.000 first record from second input archive log
194 ...
195 01:10.000 last record from second input archive log
196 The time period where the performance data is missing starts just after
198 09:15 and ends just before 09:20. When the output archive log is pro‐
199 cessed with any of the PCP reporting tools, the <mark> record is used
200 to indicate a period of missing data. For example using the output ar‐
201 chive above, imagine one was reporting the average I/O rate at 30
202 minute intervals aligned on the hour and half-hour. The I/O count met‐
203 ric is a counter, so the average I/O rate requires two valid values
204 from consecutive sample times. There would be values for all the
205 intervals ending at 09:00, then no values at 09:30 because of the
206 <mark> record, then no values at 10:00 because the ``prior'' value at
207 09:30 is not available, then the rate would be reported again at 10:30
208 and continue every 30 minutes until the last reported value at 01:00.
209 The presence of <mark> records in a PCP archive log can be established
211 using pmdumplog(1) where a timestamp and the annotation <mark> is used
212 to indicate a <mark> record.
213
215 When more than one input archive set is specified, pmlogextract per‐
216 forms a number of checks to ensure the metadata is consistent for met‐
217 rics appearing in more than one of the input archive sets. These
218 checks include:
219 * metric data type is the same
221 * metric semantics are the same
222 * metric units are the same
223 * metric is either always singular or always has the same instance
224 domain
225 * metrics with the same name have the same PMID
226 * metrics with the same PMID have the same name
227 If any of these checks fail, pmlogextract reports the details and
229 aborts without creating the output archive.
230 To address these semantic issues, use pmlogrewrite(1) to translate the
232 input archives into equivalent archives with consistent metdadata
233 before using pmlogextract.
234
236 The preamble metrics (pmcd.pmlogger.archive, pmcd.pmlogger.host, and
237 pmcd.pmlogger.port), which are automatically recorded by pmlogger at
238 the start of the archive, may not be present in the archive output by
239 pmlogextract. These metrics are only relevant while the archive is
240 being created, and have no significance once recording has finished.
241
243 All error conditions detected by pmlogextract are reported on stderr
244 with textual (if sometimes terse) explanation.
245 If one of the input archives contains no archive records then an
247 ``empty archive'' warning is issued and that archive is skipped.
248 Should one of the input archive logs be corrupted (this can happen if
250 the pmlogger instance writing the log suddenly dies), then pmlogextract
251 will detect and report the position of the corruption in the file, and
252 any subsequent information from that archive log will not be processed.
253 If any error is detected, pmlogextract will exit with a non-zero sta‐
255 tus.
256
258 For each of the input and output archive logs, several physical files
259 are used.
260 archive.meta
262 metadata (metric descriptions, instance domains, etc.) for the ar‐
263 chive log
264 archive.0
266 initial volume of metrics values (subsequent volumes have suffixes
267 1, 2, ...) - for input these files may have been previously com‐
268 pressed with bzip2(1) or gzip(1) and thus may have an additional
269 .bz2 or .gz suffix.
270 archive.index
272 temporal index to support rapid random access to the other files
273 in the archive log.
274
276 Environment variables with the prefix PCP_ are used to parameterize the
277 file and directory names used by PCP. On each installation, the file
278 /etc/pcp.conf contains the local values for these variables. The
279 $PCP_CONF variable may be used to specify an alternative configuration
280 file, as described in pcp.conf(5).
281 For environment variables affecting PCP tools, see pmGetOptions(3).
283
285 PCPIntro(1), pmdumplog(1), pmlc(1), pmlogger(1), pmlogreduce(1), pmlo‐
286 grewrite(1), pcp.conf(5), pcp.env(5) and PMNS(5).
287Performance Co-Pilot PCP PMLOGEXTRACT(1)