pmlogrewrite

Synopsis

$PCP_BINADM_DIR/pmlogrewrite [-Cdiqsvw ] [-c config] inlog [outlog]

Description

pmlogrewrite reads a set of Performance Co-Pilot (PCP) archive logs identified by inlog and creates a PCP archive log in outlog. Under normal usage, the -c option will be used to nominate a configuration file or files that contains specifications (see the Rewriting Rules Syntax section below) that describe how the data and metadata from inlog should be transformed to produce outlog.

The typical uses for pmlogrewrite would be to accommodate the evolution of Performance Metric Domain Agents (PMDAs) where the names, metadata and semantics of metrics and their associated instance domains may change over time, e.g. promoting the type of a metric from a 32-bit to a 64-bit integer, or renaming a group of metrics. Refer to the Examples section for some additional use cases.

pmlogrewrite is most useful where PMDA changes, or errors in the production environment, result in archives that cannot be combined with pmlogextract(1). By pre-processing the archives with pmlogrewrite the resulting archives may be able to be merged with pmlogextract(1).

The input inlog must be a set of PCP archive logs created by pmlogger(1), or possibly one of the tools that read and create PCP archives, e.g. pmlogextract(1) and pmlogreduce(1). inlog is a comma-separated list of names, each of which may be the base name of an archive or the name of a directory containing one or more archives.

If no -c option is specified, then the default behavior simply creates outlog as a copy of inlog. This is a little more complicated than cat(1), as each PCP archive is made up of several physical files.

While pmlogrewrite may be used to repair some data consistency issues in PCP archives, there is also a class of repair tasks that cannot be handled by pmlogrewrite and pmloglabel(1) may be a useful tool in these cases.

Options

The command line options for pmlogrewrite are as follows:

-C

Parse the rewriting rules and quit. outlog is not created. When -C is specified, this also sets -v and -w so that all warnings and verbose messages are displayed as config is parsed.

-c config

If config is a file or symbolic link, read and parse rewriting rules from there. If config is a directory, then all of the files or symbolic links in that directory (excluding those beginning with a period “.”) will be used to provide the rewriting rules. Multiple -c options are allowed.

-d

Desperate mode.  Normally if a fatal error occurs, all trace of the partially written PCP archive outlog is removed.  With the -d option, the partially created outlog archive log is not removed.

-i

Rather than creating outlog, inlog is rewritten in place when the -i option is used. A new archive is created using temporary file names and then renamed to inlog in such a way that if any errors (not warnings) are encountered, inlog remains unaltered.

-q

Quick mode, where if there are no rewriting actions to be performed (none of the global data, instance domains or metrics from inlog will be changed), then pmlogrewrite will exit (with status 0, so success) immediately after parsing the configuration file(s) and outlog is not created.

-s

When the “units” of a metric are changed, if the dimension in terms of space, time and count is unaltered, then the scaling factor is being changed, e.g. BYTE to KBYTE, or MSEC^-1 to USEC^-1, or the composite MBYTE.SEC^-1 to KBYTE.USEC^-1. The motivation may be (a) that the original metadata was wrong but the values in inlog are correct, or (b) the metadata is changing so the values need to change as well.  The default pmlogrewrite behaviour matches case (a).  If case (b) applies, then use the -s option and the values of all the metrics with a scale factor change in each result will be rescaled. For finer control over value rescaling refer to the RESCALE option for the UNITS clause of the metric rewriting rule described below.

-v

Increase verbosity of diagnostic output.

-w

Emit warnings.  Normally pmlogrewrite remains silent for any warning that is not fatal and it is expected that for a particular archive, some (or indeed, all) of the rewriting specifications may not apply.  For example, changes to a PMDA may be captured in a set of rewriting rules, but a single archive may not contain all of the modified metrics nor all of the modified instance domains and/or instances.  Because these cases are expected, they do not prevent pmlogrewrite executing, and rules that do not apply to inlog are silently ignored by default. Similarly, some rewriting rules may involve no change because the metadata in inlog already matches the intent of the rewriting rule to correct data from a previous version of a PMDA. The -w flag forces warnings to be emitted for all of these cases.

The argument outlog is required in all cases, except when -i is specified.

Rewriting Rules Syntax

A configuration file contains zero or more rewriting rules as defined below.

Keywords and special punctuation characters are shown below in bolditalic font and are case-insensitive, so METRIC, metric and Metric are all equivalent in rewriting rules.

The character “#” introduces a comment and the remainder of the line is ignored.  Otherwise the input is relatively free format with optional white space (spaces, tabs or newlines) between lexical items in the rules.

A global rewriting rule has the form:

GLOBAL { globalspec ... }

where globalspec is zero or more of the following clauses:

HOSTNAME -> hostname

Modifies the label records in the outlog PCP archive, so that the metrics will appear to have been collected from the host hostname.

TIME -> delta

Both metric values and the instance domain metadata in a PCP archive carry timestamps. This clause forces all the timestamps to be adjusted by delta, where delta is an optional sign “+” (the default) or “-”, an optional number of hours followed by a colon “:”, an optional number of minutes followed by a  colon “:”, a number of seconds, an optional fraction of seconds following a period “.”.  The simplest example would be “30” to increase the timestamps by 30 seconds.  A more complex example would be “-23:59:59.999” to move the timestamps backwards by one millisecond less than one day.

TZ -> "timezone"

Modifies the label records in the outlog PCP archive, so that the metrics will appear to have been collected from a host with a local timezone of timezone. timezone must be enclosed in quotes, and should conform to the valid timezone syntax rules for the local platform.

An indom rewriting rule modifies an instance domain and has the form:

INDOM domain.serial { indomspec ... }

where domain and serial identify one or more existing instance domains from inlog - typically domain would be an integer in the range 1 to 510 and serial would be an integer in the range 0 to 4194304.

As a special case serial could be an asterisk “*” which means the rule applies to every instance domain with a domain number of domain.

If a designated instance domain is not in inlog the rule has no effect.

The indomspec is zero or more of the following clauses:

INAME "oldname" -> "newname"

The instance identified by the external instance name oldname is renamed to newname. Both oldname and newname must be enclosed in quotes.

As a special case, the new name may be the keyword DELETE (with no quotes), and then the instance oldname will be expunged from outlog which removes it from the instance domain metadata and removes all values of this instance for all the associated metrics.

If the instance names contain any embedded spaces then special care needs to be taken in respect of the PCP instance naming rule that treats the leading non-space part of the instance name as the unique portion of the name for the purposes of matching and ensuring uniqueness within an instance domain, refer to pmdaInstance(3) for a discussion of this issue.

As an illustration, consider the hypothetical instance domain for a metric which contains 2 instances with the following names:

red
eek urk

Then some possible INAME clauses might be:

"eek" -> "yellow like a flower"

Acceptable, oldname "eek" matches the "eek urk" instance.

"red" -> "eek"

Error, newname "eek" matches the existing "eek urk" instance.

"eek urk" -> "red of another hue"

Error, newname "red of another hue" matches the existing "red" instance.

INDOM -> newdomain.newserial

Modifies the metadata for the instance domain and every metric associated with the instance domain. As a special case, newserial could be an asterisk “*” which means use serial from the indom rewriting rule, although this is most useful when serial is also an asterisk. So for example:

indom 29.* { indom -> 109.* }

will move all instance domains from domain 29 to domain 109.

INDOM -> DUPLICATE newdomain.newserial

A special case of the previous INDOM clause where the instance domain is a duplicate copy of the domain.serial instance domain from the indom rewriting rule, and then any mapping rules are applied to the copied newdomain.newserial instance domain.  This is useful when a PMDA is split and the same instance domain needs to be replicated for domain domain and domain newdomain. So for example if the metrics foo.one and foo.two are both defined over instance domain 12.34, and foo.two is moved to another PMDA using domain 27, then the following rewriting rules could be used:

indom 12.34 { indom -> duplicate 27.34 }
metric foo.two { indom -> 27.34 pmid -> 27.*.*  }

INST oldid -> newid

The instance identified by the internal instance identifier oldid is renumbered to newid. Both oldid and newid are integers in the range 0 to 2³¹-1.

As a special case, newid may be the keyword DELETE and then the instance oldid will be expunged from outlog which removes it from the instance domain metadata and removes all values of this instance for all the associated metrics.

A metric rewriting rule has the form:

METRIC metricid { metricspec ... }

where metricid identifies one or more existing metrics from inlog using either a metric name, or the internal encoding for a metric's PMID as domain.cluster.item. In the latter case, typically domain would be an integer in the range 1 to 510, cluster would be an integer in the range 0 to 4095, and item would be an integer in the range 0 to 1023.

As special cases item could be an asterisk “*” which means the rule applies to every metric with a domain number of domain and a cluster number of cluster, or cluster could be an asterisk which means the rule applies to every metric with a domain number of domain and an item number of item, or both cluster and item could be asterisks, and rule applies to every metric with a domain number of domain.

If a designated metric is not in inlog the rule has no effect.

The metricspec is zero or more of the following clauses:

A text rewriting rule modifies a help text record and has the form:

TEXT textid [ texttype ] [ "textcontent" ] { textspec ... }

where textid identifies the metric or instance domain with which the text is currently associated, and is either METRIC metricid or INDOM domain.serial.

metricid has the same form and meaning as for a METRIC rewriting rule (see above) and domain.serial has the same form and meaning as for an INDOM rewriting rule (see above).

The optional texttype identifies the type of text and may be one of ONELINE to select the one line help text, HELP to select the full help text, or ALL or an asterisk “*” to select both types of help text. If texttype is not specified, then the default is ONELINE.

The optional textcontent further restricts the selected text records to those containing the specified content. Characters such as double quotes may be escaped by preceding them with a backslash “\”.

If a designated help text record is not in inlog the rule has no effect.

The textspec is zero or more of the following clauses:

DELETE

The selected text is completely removed from outlog.

INDOM -> newdomain.newserial

Reassociates the text with the specified instance domain. As a special case, newserial could be an asterisk “*” which means use serial from the text rewriting rule, although this is most useful when serial is also an asterisk. So for example:

text indom 29.* all { indom -> 109.* }

will reassociate all text associated with instance domains from domain 29 to domain 109.

METRIC -> newdomain.newcluster.newitem

Reassociates the text with the specified metric. As special cases, newcluster could be an asterisk “*” which means use cluster from the text rewriting rule and/or item could be an asterisk which means use item from the text rewriting rule. This is most useful when cluster and/or item is also an asterisk. So for example:

text metric 30.*.* all { metric -> 123.*.* }

will reassociate all text associated with metrics from domain 30 to domain 123.

TEXT -> "new-text"

Replaces the content of the selected text with new-text.

A label rewriting rule modifies a label record and has the form:

LABEL labelid [ instance ] [ "label-name" ] [ "label-value" ] { labelspec ... }

where labelid refers to the global context or identifies the metric domain, metric cluster, metric item, instance domain, or instance domain instances with which the label is currently associated, and is either CONTEXT or DOMAIN domainid or CLUSTER domainid.clusterid or ITEM metricid or INDOM domain.serial or INSTANCES domain.serial.

metricid has the same form and meaning as for a METRIC rewriting rule (see above). clusterid may be an asterisk “*” which means the rule applies to every metric with a domain number of domainid in the same way as an asterisk may be used for the cluster within metricid.

domain.serial has the same form and meaning as for an INDOM rewriting rule (see above).

In the case of an INSTANCES labelid, the name or number of a specific instance may be optionally specified as instance. This name or number number may be omitted or specified as an asterisk “*” to indicate that labels for all instances of the specified instance domain are selected. If an instance name is specified, it must be within double quotes. If the instance name contains any embedded spaces then special care needs to be taken in respect of the PCP instance naming rule that treats the leading non-space part of the instance name as the unique portion of the name for the purposes of matching and ensuring uniqueness within an instance domain, refer to pmdaInstance(3) for a discussion of this issue.

In all cases, a "label-name" and/or a "label-value" may be optionally specified in double quotes in order to select labels with the given name and/or given value. These may individually be omitted or specified as asterisks “*” to indicate that labels with all names and/or values are selected.

If a designated label record is not in inlog the rule has no effect.

The labelspec is zero or more of the following clauses:

DELETE

The selected labels are completely removed from outlog.

NEW "new-label-name" "new-label-value"

A new label with the name "new-label-name" and the value "new-label-value" is created and associated with the specified labelid and optional instance (in the case of a INSTANCES labelid). If "label-name" or "label-value" were specified, then they are ignored with a warning. If instance is not specified for an INSTANCES labelid, then a new label will be created for each instance in the specified instance domain.

LABEL -> "new-label-name"

The name of the selected label(s) is changed to "new-label-name".

VALUE -> "new-label-value"

The value of the selected label(s) is changed to "new-label-value".

DOMAIN -> newdomain

Reassociates the selected label(s) with the specified metric domain. For example:

label domain 30 { domain -> 123 }

will reassociate all labels associated with domains from domain 30 to domain 123.

CLUSTER -> newdomain.newcluster

Reassociates the selected label(s) with the specified metric cluster. As a special case, newcluster could be an asterisk “*” which means use cluster from the label rewriting rule. This is most useful when cluster is also an asterisk. So for example:

label cluster 30.* { cluster -> 123.* }

will reassociate all labels associated with clusters from domain 30 to domain 123.

ITEM -> newdomain.newcluster.newitem

Reassociates the selected label(s) with the specified metric item. As special cases, newcluster could be an asterisk “*” which means use cluster from the label rewriting rule and/or item could be an asterisk which means use item from the label rewriting rule. This is most useful when cluster and/or item is also an asterisk. So for example:

label item 30.*.* { item -> 123.*.* }

will reassociate all labels associated with metrics from domain 30 to domain 123.

INDOM -> newdomain.newserial

Reassociates the selected label(s) with the specified instance domain. As a special case, newserial could be an asterisk “*” which means use serial from the label rewriting rule, although this is most useful when serial is also an asterisk. So for example:

label indom 29.* { indom -> 109.* }

will reassociate all labels associated with instance domains from domain 29 to domain 109.

INSTANCES -> newdomain.newserial

This is the same as INDOM except that it reassociates the selected label(s) with the instances of the specified instance domain.

Examples

To promote the values of the per-disk IOPS metrics to 64-bit to allow aggregation over a long time period for capacity planning, or because the PMDA has changed to export 64-bit counters and we want to convert old archives so they can be processed alongside new archives.

metric disk.dev.read { type -> U64 }
metric disk.dev.write { type -> U64 }
metric disk.dev.total { type -> U64 }

The instances associated with the load average metric kernel.all.load could be renamed and renumbered by the rules below.

# for the Linux PMDA, the kernel.all.load metric is defined
# over instance domain 60.2
indom 60.2 {
    inst 1 -> 60 iname "1 minute" -> "60 second"
    inst 5 -> 300 iname "5 minute" -> "300 second"
    inst 15 -> 900 iname "15 minute" -> "900 second"
}

If we decide to split the “proc” metrics out of the Linux PMDA, this will involve changing the domain number for the PMID of these metrics and the associated instance domains.  The rules below would rewrite an old archive to match the changes after the PMDA split.

# all Linux proc metrics are in 7 clusters
metric 60.8.* { pmid -> 123.*.* }
metric 60.9.* { pmid -> 123.*.* }
metric 60.13.* { pmid -> 123.*.* }
metric 60.24.* { pmid -> 123.*.* }
metric 60.31.* { pmid -> 123.*.* }
metric 60.32.* { pmid -> 123.*.* }
metric 60.51.* { pmid -> 123.*.* }
# only one instance domain for Linux proc metrics
indom 60.9 { indom -> 123.0 }

If the metric foo.count_em was exported as a native “long” then it could be a 32-bit integer on some platforms and a 64-bit integer on other platforms.  Subsequent investigations show the value is in fact unsigned, so the following rules could be used.

metric foo.count_em {
	type if 32 -> U32
	type if 64 -> U64
}

Files

For each of the inlog and outlog archive logs, several physical files are used.

archive.meta

metadata (metric descriptions, instance domains, etc.) for the archive log

archive.0

initial volume of metrics values (subsequent volumes have suffixes 1, 2, ...).

archive.index

temporal index to support rapid random access to the other files in the archive log.

PCP Environment

Environment variables with the prefix PCP_ are used to parameterize the file and directory names used by PCP. On each installation, the file /etc/pcp.conf contains the local values for these variables. The $PCP_CONF variable may be used to specify an alternative configuration file, as described in pcp.conf(5).

See Also

PCPIntro(1), pmdaInstance(3), pmdumplog(1), pmlogger(1), pmlogextract(1), pmloglabel(1), pmlogreduce(1), pmLookupDesc(3), pcp.conf(5), pcp.env(5) and PMNS(5).

Diagnostics

All error conditions detected by pmlogrewrite are reported on stderr with textual (if sometimes terse) explanation.

Should the input archive log be corrupted (this can happen if the pmlogger instance writing the log suddenly dies), then pmlogrewrite will detect and report the position of the corruption in the file, and any subsequent information from that archive log will not be processed.

If any error is detected, pmlogrewrite will exit with a non-zero status.

Referenced By

LOGARCHIVE(5), pmdaExtGetData(3), pmdaperfevent(1), pmlogcheck(1), pmlogextract(1), pmlogger_check(1), pmlogger_rewrite(1), pmloglabel(1).