1LOGARCHIVE(5) File Formats Manual LOGARCHIVE(5)
2
6 LOGARCHIVE - Performance Co-Pilot archive formats
7
9 Performance Co-Pilot (PCP) archives store historical values about arbi‐
10 trary metrics recorded from a single host. Archives are machine inde‐
11 pendent and self-contained - all metric data and metadata required for
12 off-line or off-site analysis is held within an archive.
13 The format is stable in order to allow long-term historical storage and
15 processing by PMAPI(3) client tools. However some format variants are
16 supported over time, and currently Versions 2 and 3 are supported. The
17 mandate is that PCP will provide long-term backwards compatibility, so
18 an archive created on any version of PCP can be read on that version of
19 PCP and all subsequent versions of PCP. The exception is Version 1
20 that was retired in the PCP Version 2.0 release in May 1998.
21 Archives may be read by most PCP client tools, using the -a/--archive
23 NAME option, or dumped raw by pmdumplog(1). Archives are created pri‐
24 marily by pmlogger(1), however they can also be created using the
25 LOGIMPORT(3) programming interface.
26 Archives may be merged, analyzed, modified and subsampled using pmlo‐
28 greduce(1), pmlogsummary(1), pmlogrewrite(1) and pmlogextract(1). In
29 addition, PCP archives may be examined in sets or grouped together into
30 ``archive folios'', which are created and managed by the mkaf(1) and
31 pmafm(1) tools.
32 An archive consists of several physical files that share a common arbi‐
34 trary prefix, e.g. myarchive.
35 myarchive.0, myarchive.1, ...
37 One or more data volumes containing the metric values and any
38 error codes encountered during metric sampling. Typically the
39 largest of the files and may grow very rapidly, depending on the
40 selection of metrics to be logged by pmlogger(1) and the sam‐
41 pling intervals being used.
42 myarchive.meta
44 Information for PMAPI functions such as pmLookupName(3), pm‐
45 LookupDesc(3), pmLookupLabels(3) and pmLookupInDom(3). The
46 metadata file may grow sporadically as logged metrics, instance
47 domains and labels vary over time.
48 myarchive.index
50 A temporal index, mapping timestamps to byte offsets in the
51 other files.
52
54 All three types of files have a similar record-based structure, a con‐
55 vention of network byte-order (big-endian) encoding, and 32-bit fields
56 for tagging/padding for those records. Strings are stored as 8-bit
57 characters without assuming a specific encoding, so normally ASCII.
58 See also the __pmLog* types in src/include/pcp/libpcp.h.
59 RECORD FRAMING
62 The volume and .meta files are divided into self-identifying records.
63 ┌───────┬────────┬─────────────────────────────────────────────────────┐
65 │Offset │ Length │ Name │
66 ├───────┼────────┼─────────────────────────────────────────────────────┤
67 │ 0 │ 4 │ N, length of record, in bytes, including this field │
68 │ 4 │ N-8 │ record payload, usually starting with a 32-bit │
69 │ │ │ record type tag │
70 │ N-4 │ 4 │ N, length of record (again) │
71 └───────┴────────┴─────────────────────────────────────────────────────┘
72 ARCHIVE LABEL
74 All three types of files begin with an ``archive label'' header, which
75 identifies the host name, starting timestamp and timezone information;
76 all referring to the host that was the source of the performance data
77 (which may be different to the host where pmlogger(1) was running).
78 The ``archive label'' format differs between Version 2 and Version 3,
80 with the latter providing enhanced timestamps (64-bit encoding of the
81 seconds part and nanosecond precision) and some additional fields.
82 ┌──────────────────────────────────────────────────────────────────────┐
85 │ Version 2 │
86 ├───────┬────────┬─────────────────────────────────────────────────────┤
87 │Offset │ Length │ Name │
88 ├───────┼────────┼─────────────────────────────────────────────────────┤
89 │ 0 │ 4 │ tag, PM_LOG_MAGIC | PM_LOG_VERS02=0x50052602 │
90 │ 4 │ 4 │ process id (PID) of pmlogger process that wrote │
91 │ │ │ file │
92 │ 8 │ 4 │ archive start time, seconds part (past UNIX epoch) │
93 │ 12 │ 4 │ archive start time, microseconds part │
94 │ 16 │ 4 │ current archive volume number (or -1=.meta, │
95 │ │ │ -2=.index) │
96 │ 20 │ 64 │ name of collection host │
97 │ 80 │ 40 │ time zone string for collection host ($TZ │
98 │ │ │ environment variable) │
99 └───────┴────────┴─────────────────────────────────────────────────────┘
100 ┌──────────────────────────────────────────────────────────────────────┐
102 │ Version 3 │
103 ├───────┬────────┬─────────────────────────────────────────────────────┤
104 │Offset │ Length │ Name │
105 ├───────┼────────┼─────────────────────────────────────────────────────┤
106 │ 0 │ 4 │ tag, PM_LOG_MAGIC | PM_LOG_VERS03=0x50052603 │
107 │ 4 │ 4 │ PID of pmlogger process that wrote file │
108 │ 8 │ 8 │ archive start time, seconds part (past UNIX epoch) │
109 │ 16 │ 4 │ archive start time, nanoseconds part │
110 │ 20 │ 4 │ current archive volume number (or -1=.meta, │
111 │ │ │ -2=.index) │
112 │ 24 │ 4 │ archive feature bits │
113 │ 28 │ 4 │ reserved for future use │
114 │ 32 │ 256 │ name of collection host │
115 │ 288 │ 256 │ timezone string for collection host ($TZ │
116 │ │ │ environment variable), e.g. AEDT-11 │
117 │ 544 │ 256 │ timezone zoneinfo string for collection host, e.g. │
118 │ │ │ :Australia/Melbourne │
119 └───────┴────────┴─────────────────────────────────────────────────────┘
120 The ``archive feature bits'' are intended to encode possible future
122 extensions or differences to the on-disk structure or the the archive
123 semantics. At this stage there are no such features, but if they are
124 introduced at some point in the future, there will be associated
125 PM_LOG_FEATURE_XXX macros added to the <pcp/pmapi.h> header file.
126 All fields, except for the ``current archive volume number'', match for
129 all files in a single PCP archive.
130
133 pmResult
134 After the archive label record, an archive volume file contains one or
135 more records, each providing metric values corresponding to the
136 pmResult from one pmFetch(3) operation. The record size may vary
137 according to number of metrics being fetched and the number of
138 instances in the associated instance domains.
139 For Version 2 the file size is limited to 2GiB, due to storage of
141 32-bit byte offsets within the temporal index. For Version 3 the file
142 size is limited to 8191PiB, due to storage of 62-bit byte offsets
143 within the temporal index.
144 The pmResult format differs between Version 2 and Version 3, with the
146 latter providing enhanced timestamps (64-bit encoding of the seconds
147 part and nanosecond precision).
148 ┌─────────────────────────────────────────────────────────────┐
151 │ Version 2 │
152 ├────────┬────────┬───────────────────────────────────────────┤
153 │Offset │ Length │ Name │
154 ├────────┼────────┼───────────────────────────────────────────┤
155 │ 0 │ 4 │ timestamp, seconds part (past UNIX epoch) │
156 │ 4 │ 4 │ timestamp, microseconds part │
157 │ 8 │ 4 │ number of metrics with data following │
158 │ 12 │ M │ pmValueSet #0 │
159 │ 12+M │ N │ pmValueSet #1 │
160 │ 12+M+N │ ... │ ... │
161 │ NOP │ X │ pmValueBlock #0 │
162 │ NOP+X │ Y │ pmValueBlock #1 │
163 │NOP+X+Y │ ... │ ... │
164 └────────┴────────┴───────────────────────────────────────────┘
165 ┌─────────────────────────────────────────────────────────────┐
167 │ Version 3 │
168 ├────────┬────────┬───────────────────────────────────────────┤
169 │Offset │ Length │ Name │
170 ├────────┼────────┼───────────────────────────────────────────┤
171 │ 0 │ 8 │ timestamp, seconds part (past UNIX epoch) │
172 │ 8 │ 4 │ timestamp, nanoseconds part │
173 │ 12 │ 4 │ number of metrics with data following │
174 │ 16 │ M │ pmValueSet #0 │
175 │ 16+M │ N │ pmValueSet #1 │
176 │ 16+M+N │ ... │ ... │
177 │ NOP │ X │ pmValueBlock #0 │
178 │ NOP+X │ Y │ pmValueBlock #1 │
179 │NOP+X+Y │ ... │ ... │
180 └────────┴────────┴───────────────────────────────────────────┘
181 Records with a ``number of metrics'' equal to zero are ``mark
183 records'', and represent interruptions, missing data, or time
184 discontinuities in logging.
185 pmValueSet
187 This subrecord represents the values for one metric at one point in
188 time.
189 ┌───────┬────────┬────────────────────────────────────────────────┐
191 │Offset │ Length │ Name │
192 ├───────┼────────┼────────────────────────────────────────────────┤
193 │ 0 │ 4 │ Performance Metrics Identifier (PMID) │
194 │ 4 │ 4 │ number of values │
195 │ 8 │ 4 │ value format, PM_VAL_INSITU=0 or PM_VAL_DPTR=1 │
196 │ 12 │ M │ pmValue #0 │
197 │ 12+M │ N │ pmValue #1 │
198 │12+M+N │ ... │ ... │
199 └───────┴────────┴────────────────────────────────────────────────┘
200 The metadata describing metrics is found in the .meta file where the
202 entries are not timestamped, as the metadata is assumed to be
203 unchanging throughout an archive.
204 pmValue
206 This subrecord represents one value for one instance of a metric at one
207 point in time. It is a variant type, depending on the parent
208 pmValueSet's value format field. This allows small numbers to be
209 encoded compactly, but retain flexibility for larger or variable length
210 data to be stored later in the pmResult record in a pmValueBlock
211 subrecord.
212 ┌───────┬────────┬─────────────────────────────────────────────────────┐
214 │Offset │ Length │ Name │
215 ├───────┼────────┼─────────────────────────────────────────────────────┤
216 │ 0 │ 4 │ internal instance identifier (or PM_IN_NULL=-1 for │
217 │ │ │ singular metrics) │
218 │ 4 │ 4 │ value (INSITU) or │
219 │ │ │ offset in pmResult to our pmValueBlock (DPTR) │
220 └───────┴────────┴─────────────────────────────────────────────────────┘
221 The metadata describing the instance domain for metrics is found in the
223 .meta file. Since the numeric mappings may change during the lifetime
224 of the logging session, it is important to match up the timestamp of
225 the measurement record with the corresponding instance domain record.
226 That is, the instance domain corresponding to a measurement at time T
227 is the instance domain observation for the metric's instance domain
228 with largest timestamp T' <= T.
229 pmValueBlock
232 Instances of this subrecord are placed at the end of the pmValueSet,
233 after all the pmValue subrecords. If (and only if) needed, they are
234 padded at the end to the next 32-bit boundary.
235 ┌───────┬────────┬────────────────────────────────────────────────┐
237 │Offset │ Length │ Name │
238 ├───────┼────────┼────────────────────────────────────────────────┤
239 │ 0 │ 1 │ value type (same as pmDesc.type) │
240 │ 1 │ 3 │ 4 + N, the length of the subrecord │
241 │ 4 │ N │ bytes that make up the raw value │
242 │ 4+N │ 0-3 │ padding (not included in the 4+N length field) │
243 └───────┴────────┴────────────────────────────────────────────────┘
244 Note that for PM_TYPE_STRING, the length includes an explicit NULL
246 terminator byte. For PM_TYPE_EVENT, the value byte string is further
247 structured. Refer to PMDAEVENTARRAY(3) for more information about how
248 arrays of event records are packed inside a pmResult container.
249
252 After the archive label record, the metadata file contains interleaved
253 metric description records, timestamped instance domain records,
254 timestamped label records (for context, instance domain and metric
255 labels) and (help) text records. Unlike the data volumes, these
256 records are not forced to 32-bit alignment.
257 For Version 2 the file size is limited to 2GiB, due to storage of
259 32-bit byte offsets within the temporal index. For Version 3 the file
260 size is limited to 8191PiB, due to storage of 62-bit byte offsets
261 within the temporal index.
262 See also libpcp/src/logmeta.c.
264 Metric Descriptions
266 Instances of this (pmDesc) record provide the description or metadata
267 for each metric appearing in the PCP archive. This metadata includes
268 the metric's PMID, data type, data semantics, instance domain
269 identifier (or PM_INDOM_NULL for singular metrics with only one value)
270 and a set of (1 or more) names.
271 ┌───────┬────────┬───────────────────────────────────────────────────┐
273 │Offset │ Length │ Name │
274 ├───────┼────────┼───────────────────────────────────────────────────┤
275 │ 0 │ 4 │ tag, TYPE_DESC=1 │
276 │ 4 │ 4 │ PMID │
277 │ 8 │ 4 │ data type (PM_TYPE_*) │
278 │ 12 │ 4 │ instance domain identifier │
279 │ 16 │ 4 │ metric semantics (PM_SEM_*) │
280 │ 20 │ 4 │ units: bit-packed pmUnits │
281 │ 4 │ 4 │ number of alternative names for this PMID │
282 │ 28 │ 4 │ N: number of bytes in this name │
283 │ 32 │ N │ bytes of the name, no NULL terminator nor padding │
284 │ 32+N │ 4 │ N2: number of bytes in next name │
285 │ 36+N │ N2 │ bytes of the name, no NULL terminator nor padding │
286 │ ... │ ... │ ... │
287 └───────┴────────┴───────────────────────────────────────────────────┘
288 Instance Domains
290 A set-valued metric is defined over an instance domain, which consists
291 of an instance domain identifier (will have already been mentioned in a
292 prior pmDesc record), a count of the number of instances and a map that
293 defines the association between internal instance identifiers
294 (integers) and external instance names (strings).
295 Because instance domains can change over time, the instance domain also
297 requires a timestamp, and the same instance domain can occur multiple
298 times within the .meta file. The timestamps are used to search for the
299 temporally correct instance domain when decoding pmResult records from
300 the archive data volumes, or answering metadata queries against the
301 instance domain.
302 The instance domain format differs markedly between Version 2 and
304 Version 3. Version 3 provides enhanced timestamps (64-bit encoding of
305 the seconds part and nanosecond precision) and introduces a new
306 ``delta'' instance domain format that encodes differences between the
307 previous observation of the instance domain and the current state of
308 the instance domain.
309 ┌──────────────────────────────────────────────────────────────────┐
312 │ Full Instance Domain - Version 2 │
313 ├─────────┬────────┬───────────────────────────────────────────────┤
314 │ Offset │ Length │ Name │
315 ├─────────┼────────┼───────────────────────────────────────────────┤
316 │ 0 │ 4 │ tag, TYPE_INDOM_V2=2 │
317 │ 4 │ 4 │ timestamp, seconds part (past UNIX epoch) │
318 │ 8 │ 4 │ timestamp, microseconds part │
319 │ 12 │ 4 │ instance domain number │
320 │ 16 │ 4 │ N: number of instances in domain, normally >0 │
321 │ 20 │ 4 │ first instance number │
322 │ 24 │ 4 │ second instance number (if appropriate) │
323 │ ... │ ... │ ... │
324 │ 20+4*N │ 4 │ first offset into string table (see below) │
325 │20+4*N+4 │ 4 │ second offset into string table (etc.) │
326 │ ... │ ... │ ... │
327 │ 20+8*N │ M │ base of string table, containing │
328 │ │ │ packed, NULL-terminated instance names │
329 └─────────┴────────┴───────────────────────────────────────────────┘
330 ┌──────────────────────────────────────────────────────────────────┐
332 │ Full Instance Domain - Version 3 │
333 ├─────────┬────────┬───────────────────────────────────────────────┤
334 │ Offset │ Length │ Name │
335 ├─────────┼────────┼───────────────────────────────────────────────┤
336 │ 0 │ 4 │ tag, TYPE_INDOM=5 │
337 │ 4 │ 8 │ timestamp, seconds part (past UNIX epoch) │
338 │ 12 │ 4 │ timestamp, nanoseconds part │
339 │ 16 │ 4 │ instance domain number │
340 │ 20 │ 4 │ N: number of instances in domain, normally >0 │
341 │ 24 │ 4 │ first instance number │
342 │ 28 │ 4 │ second instance number (if appropriate) │
343 │ ... │ ... │ ... │
344 │ 24+4*N │ 4 │ first offset into string table (see below) │
345 │24+4*N+4 │ 4 │ second offset into string table (etc.) │
346 │ ... │ ... │ ... │
347 │ 24+8*N │ M │ base of string table, containing │
348 │ │ │ packed, NULL-terminated instance names │
349 └─────────┴────────┴───────────────────────────────────────────────┘
350 The ``delta'' instance domain record in Version 3 uses the same
352 physical structure as the ``full'' instance domain above with the
353 following differences:
354 * The tag is TYPE_INDOM_DELTA=6.
355 * The ``number of instances in domain'' field becomes the sum of the
356 number of instances added and the number of instances deleted.
357 * Deleted instances are encoded with the string offset set to -1 and
358 there is no corresponding string table entry.
359 * Added instances are encoded exactly the same way.
360 The ``delta'' instance domain format is used to provide a more compact
363 on-disk encoding for instance domains that have a large number of
364 instances and are subject to frequent small changes, e.g. the instance
365 domain of process ids, as exported by pmdaproc(1).
366 For ``full'' instance domain records the instance domain replace the
369 previous instance domain: prior records are not searched for instance
370 domain metadata queries after this timestamp.
371 Each instance domain in a Version 3 archive must have an initial
374 ``full'' instance domain record. Subsequent records for the same
375 instance domain can be the `full'' or the ``delta'' variant. Any
376 instance mentioned in the prior observation of an instance domain that
377 is not mentioned in the ``delta'' instance domain record is assumed to
378 continue to exist for the current observation of the instance domain.
379 Labels for Contexts, Instance Domains and Metrics
382 Instances of this (pmLogLabelSet) record provide sets of label-
383 name:label-value pairs associated with labels of the context, instance
384 domains and individual performance metrics - refer to pmLookupLabels(3)
385 for further details.
386 Any instance domain identifier will have already been mentioned in a
388 prior pmDesc record.
389 As new labels can appear during an archiving session, these records are
391 timestamped and must be searched when decoding pmResult records from
392 the archive data volumes. The pmLogLabelSet format differs between
393 Version 2 and Version 3, with the latter providing enhanced timestamps
394 (64-bit encoding of the seconds part and nanosecond precision).
395 ┌──────────────────────────────────────────────────────────────────────┐
398 │ Version 2 │
399 ├────────────┬────────┬────────────────────────────────────────────────┤
400 │ Offset │ Length │ Name │
401 ├────────────┼────────┼────────────────────────────────────────────────┤
402 │ 0 │ 4 │ tag, TYPE_LABEL_V2=3 │
403 │ 4 │ 4 │ timestamp, seconds part (past UNIX epoch) │
404 │ 8 │ 4 │ timestamp, microseconds part │
405 │ 12 │ 4 │ label type (PM_LABEL_* type macros.) │
406 │ 16 │ 4 │ numeric identifier - domain, PMID, etc or │
407 │ │ │ PM_IN_NULL=-1 for context labels │
408 │ 20 │ 4 │ N: number of label sets in this record, │
409 │ │ │ usually 1 except in the case of instances │
410 │ 24 │ 4 │ offset to the start of the JSONB labels string │
411 │ 28 │ L1 │ first labelset array entry (see below) │
412 │ ... │ ... │ ... │
413 │ 28+L1 │ LN │ N-th labelset array entry (see below) │
414 │ ... │ ... │ ... │
415 │28+L1+...LN │ M │ concatenated JSONB strings for all labelsets │
416 └────────────┴────────┴────────────────────────────────────────────────┘
417 ┌──────────────────────────────────────────────────────────────────────┐
419 │ Version 3 │
420 ├────────────┬────────┬────────────────────────────────────────────────┤
421 │ Offset │ Length │ Name │
422 ├────────────┼────────┼────────────────────────────────────────────────┤
423 │ 0 │ 4 │ tag, TYPE_LABEL=7 │
424 │ 4 │ 8 │ timestamp, seconds part (past UNIX epoch) │
425 │ 12 │ 4 │ timestamp, nanoseconds part │
426 │ 16 │ 4 │ label type (PM_LABEL_* type macros.) │
427 │ 20 │ 4 │ numeric identifier - domain, PMID, etc or │
428 │ │ │ PM_IN_NULL=-1 for context labels │
429 │ 24 │ 4 │ N: number of label sets in this record, │
430 │ │ │ usually 1 except in the case of instances │
431 │ 28 │ 4 │ offset to the start of the JSONB labels string │
432 │ 32 │ L1 │ first labelset array entry (see below) │
433 │ ... │ ... │ ... │
434 │ 32+L1 │ LN │ N-th labelset array entry (see below) │
435 │ ... │ ... │ ... │
436 │32+L1+...LN │ M │ concatenated JSONB strings for all labelsets │
437 └────────────┴────────┴────────────────────────────────────────────────┘
438 Records of this form replace the existing labels for a given label
440 type: prior records are not searched for resolving that class of label
441 in measurements after this timestamp.
442 The individual labelset array entries are variable length, depending on
444 the number of labels present within that set. These entries contain
445 the instance identifiers (in the case of type PM_LABEL_INSTANCES
446 labels), lengths and offsets of each label name and value, and also any
447 flags set for each label.
448 ┌───────┬────────┬───────────────────────────────────────────┐
450 │Offset │ Length │ Name │
451 ├───────┼────────┼───────────────────────────────────────────┤
452 │ 0 │ 4 │ instance identifier (or PM_IN_NULL=-1) │
453 │ 4 │ 4 │ length of JSONB label string │
454 │ 8 │ 4 │ N: number of labels in this labelset │
455 │ 12 │ 2 │ first label name offset │
456 │ 14 │ 1 │ first label name length │
457 │ 15 │ 1 │ first label flags (e.g. optionality) │
458 │ 16 │ 2 │ first label value offset │
459 │ 18 │ 2 │ first label value length │
460 │ 20 │ 2 │ second label name offset (if appropriate) │
461 │ ... │ ... │ ... │
462 └───────┴────────┴───────────────────────────────────────────┘
463 Help Text
465 This (pmLogText) record stores help text associated with a metric or an
466 instance domain - as provided by pmLookupText(3) and
467 pmLookupInDomText(3).
468 The metric identifier and instance domain identifier will have already
470 been mentioned in a prior pmDesc record.
471 ┌───────┬────────┬──────────────────────────────────────────────┐
474 │Offset │ Length │ Name │
475 ├───────┼────────┼──────────────────────────────────────────────┤
476 │ 0 │ 4 │ tag, TYPE_TEXT=4 │
477 │ 4 │ 4 │ text and identifier type (PM_TEXT_* macros.) │
478 │ 8 │ 4 │ numeric identifier - PMID or instance domain │
479 │ 12 │ M │ help text string, arbitrary text │
480 └───────┴────────┴──────────────────────────────────────────────┘
481
483 After the archive label record, the temporal index file contains a
484 plainly concatenated, unframed group of tuples, which relate timestamps
485 to the byte offsets in the volume and .meta files. These records are
486 fixed size, fixed format, and are not enclosed in the standard
487 length/payload/length wrapper: they take up the entire remainder of the
488 .index file after the archive label record.
489 The temporal index file provides a rapid way of seeking to a particular
491 point of time within an archive for both the performance metric values
492 and the associated metadata.
493 See also libpcp/src/logutil.c.
495 The index format differs between Version 2 and Version 3, with the
497 latter providing enhanced timestamps (64-bit encoding of the seconds
498 part and nanosecond precision) and 64-bit byte offsets.
499 ┌────────────────────────────────────────────────────────────┐
502 │ Version 2 │
503 ├───────┬────────┬───────────────────────────────────────────┤
504 │Offset │ Length │ Name │
505 ├───────┼────────┼───────────────────────────────────────────┤
506 │ 0 │ 4 │ timestamp, seconds part (past UNIX epoch) │
507 │ 4 │ 4 │ timestamp, microseconds part │
508 │ 8 │ 4 │ archive volume number (0...N) │
509 │ 12 │ 4 │ byte offset in .meta file │
510 │ 16 │ 4 │ byte offset in archive volume file │
511 └───────┴────────┴───────────────────────────────────────────┘
512 ┌────────────────────────────────────────────────────────────┐
514 │ Version 3 │
515 ├───────┬────────┬───────────────────────────────────────────┤
516 │Offset │ Length │ Name │
517 ├───────┼────────┼───────────────────────────────────────────┤
518 │ 0 │ 8 │ timestamp, seconds part (past UNIX epoch) │
519 │ 8 │ 4 │ timestamp, nanoseconds part │
520 │ 12 │ 4 │ archive volume number (0...N) │
521 │ 16 │ 8 │ byte offset in .meta file │
522 │ 24 │ 8 │ byte offset in archive volume file │
523 └───────┴────────┴───────────────────────────────────────────┘
524 Since the temporal index is optional, and exists only to speed up time-
526 based random access to metrics and their metadata, the index records
527 are emitted only intermittently. An archive reader program should not
528 presume any particular rate of data flow into the index. However,
529 common events that may trigger a new temporal index record include
530 changes in instance domains, switching over to a new archive volume,
531 and starting or stopping logging. One reliable invariant however is
532 that, for each index entry, there are to be no meta or archive volume
533 records with a timestamp after that in the index, but physically before
534 the associated byte offset in the index.
535
538 Several PCP tools create archives in standard locations:
539 $HOME/.pcp/pmlogger
541 default location for the interactive chart recording mode in
542 pmchart(1)
543 $PCP_LOG_DIR/pmlogger
544 default location for pmlogger_daily(1) and pmlogger_check(1)
545 scripts
546
548 mkaf(1), PCPIntro(1), pmafm(1), pmchart(1), pmdaproc(1), pmdumplog(1),
549 pmlogger(1), pmlogger_check(1), pmlogger_daily(1), pmlogreduce(1),
550 pmlogrewrite(1), pmlogsummary(1), LOGIMPORT(3), PMAPI(3),
551 pmLookupDesc(3), pmLookupInDom(3), pmLookupInDomText(3),
552 pmLookupLabels(3), pmLookupName(3), pmLookupText(3), pcp.conf(5) and
553 pcp.env(5).
554Performance Co-Pilot LOGARCHIVE(5)