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   pmlogger    ( 1 )

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Описание (Description)

pmlogger creates the archive logs of performance metric values that may be ``played back'' by other Performance Co-Pilot (see PCPIntro(1)) tools. These logs form the basis of the VCR paradigm and retrospective performance analysis services common to the PCP toolkit.

The mandatory argument archive is the base name for the physical files that constitute an archive log. The archive argument may contain strftime(3) meta-characters, which will be substituted prior to creating the archive log files. When pmlogger is run as a service (see pmlogger_daily(1)), the standard archive base name template is %Y%m%d.%H.%M.

The -V option specifies the version for the archive that is generated. By default a version 2 archive is generated, and the only value currently supported for version is 2.

Unless directed to another host by the -h option or when directly using PMDAs via the -o option, pmlogger will contact the Performance Metrics Collector Daemon (PMCD) on the local host and use that as the source of the metric values to be logged.

To support the required flexibility and control over what is logged and when, pmlogger maintains an independent two level logging state for each instance of each performance metric. At the first (mandatory) level, logging is allowed to be on (with an associated interval between samples), or off or maybe. In the latter case, the second (advisory) level logging is allowed to be on (with an associated interval between samples), or off.

The mandatory level allows universal specification that some metrics must be logged, or must not be logged. The default state for all instances of all metrics when pmlogger starts is mandatory maybe and advisory off.

Use pmlc(1) to interrogate and change the logging state once pmlogger is running.

If a metric's state is mandatory (on or off) and a request is made to change it to mandatory maybe, the new state is mandatory maybe and advisory off. If a metric's state is already advisory (on or off) and a request is made to change it to mandatory maybe, the current state is retained.

It is not possible for pmlogger to log specific instances of a metric and all instances of the same metric concurrently. If specific instances are being logged and a request to log all instances is made, then all instances of the metric will be logged according to the new request, superseding any prior logging request for the metric. A request to log all instances of a metric will supersede any previous request to log all instances. A request to log specific instances of a metric when all instances are already being logged is refused. To do this one must turn off logging for all instances of the metric first. In each case, the validity of the request is checked first; for example a request to change a metric's logging state to advisory on when it is currently mandatory off is never permitted (it is necessary to change the state to mandatory maybe first).

Optionally, each system running pmcd(1) may also be configured to run a ``primary'' pmlogger instance. This pmlogger instance is launched by $PCP_RC_DIR/pmlogger, and is affected by the files $PCP_SYSCONF_DIR/pmlogger/control, $PCP_SYSCONF_DIR/pmlogger/control.d (use chkconfig(8), systemctl(1) or similar platform-specific commands to activate or disable the primary pmlogger instance), $PCP_SYSCONFIG_DIR/pmlogger (environment variable settings for the primary pmlogger) $PCP_SYSCONF_DIR/pmlogger/pmlogger.options (command line options passed to the primary pmlogger) and $PCP_VAR_DIR/config/pmlogger/config.default (the default initial configuration file for the primary pmlogger).

The primary pmlogger instance is identified by the -P option. There may be at most one ``primary'' pmlogger instance on each system. The primary pmlogger instance (if any) must be running on the same host as the pmcd(1) to which it connects (if any), so the -h and -P options are mutually exclusive.

Logging of some metrics is possible even in the absence of a local pmcd(1), using the "local context" mode of operation. This is activated using the -o option, and causes pmlogger to make use of local DSO PMDAs instead of communicating with pmcd(1). When operating using a local context, the -K option may be used to control the DSO PMDAs that should be made accessible. The spec argument conforms to the syntax described in pmSpecLocalPMDA(3). More than one -K option may be used.

When launched as a non-primary instance, pmlogger will exit immediately if the configuration file causes no metric logging to be scheduled. The -L option overrides this behavior, and causes a non-primary pmlogger instance to ``linger'', presumably pending some future dynamic re-configuration and state change via pmlc(1). pmlogger will also linger without the -L option being used if all the metrics to be logged are logged as once only metrics. When the once only metrics have been logged, a warning message will be generated stating that the event queue is empty and no more events will be scheduled.

By default all diagnostics and errors from pmlogger are written to the file pmlogger.log in the directory where pmlogger is launched. The -l option may be used to override the default behavior. If the log file cannot be created or is not writable, output is written to standard error instead. If the logfile for the -l option is "-" (i.e. -l-) then log messages are written to the standard output stream. This can be particularly useful when running pmlogger manually, rather than as a service daemon.

The -N option directs pmlogger to notify a service manager, typically systemd(1), when it has started and is about to begin writing PCP archive logs. This option would only normally be used when pmlogger is run as a daemon service under the control of a service manager. For more details, see __pmServerNotifyServiceManagerReady(3) and systemd(1). On platforms that do not use a service manager that supports notifications, the -N option is basically a no-op.

If specified, the -s option instructs pmlogger to terminate after a certain size in records, bytes or time units has been accumulated. If endsize is an integer then endsize records will be written to the log. If endsize is an integer suffixed by b or bytes then endsize bytes of the archive data will be written out (note, however, that archive log record boundaries will not be broken and so this limit may be slightly surpassed). Other viable file size units include: K, Kb, KiB, Kbyte, Kilobyte for kilobytes and M, Mb, MiB, Mbyte, Megabyte for megabytes and G, Gb, GiB, Gbyte, Gigabyte for gigabytes. These units may be optionally suffixed by an s and may be of mixed case. Alternatively endsize may be an integer or a floating point number suffixed using a time unit as described in PCPIntro(1) for the interval argument (to the standard PCP -t command line option). Some examples of different formats: -s 100 -s 100bytes -s 100K -s 100Mb -s 10Gbyte -s 10mins -s 1.5hours The default is for pmlogger to run forever.

The -r option causes the size of the physical record(s) for each group of metrics and the expected contribution of the group to the size of the PCP archive for one full day of collection to be reported in the log file. This information is reported the first time each group is successfully written to the archive.

The -U option specifies the user account under which to run pmlogger. The default is the current user account for interactive use. When run as a daemon, the unprivileged "pcp" account is used in current versions of PCP, but in older versions the superuser account ("root") was used by default.

The log file is potentially a multi-volume data set, and the -v option causes pmlogger to start a new volume after a certain size in records, bytes, or time units has been accumulated for the current volume. The format of this size specification is identical to that of the -s option (see above). The default is for pmlogger to create a single volume log. Additional volume switches can also be forced asynchronously by either using pmlc(1) or sending pmlogger a SIGHUP signal (see below). Note, if a scheduled volume switch is in operation due to the -v option, then its counters will be reset after an asynchronous switch.

Independent of any -v option, each volume of an archive is limited to no more than 2^31 bytes, so pmlogger will automatically create a new volume for the archive before this limit is reached.

Normally pmlogger operates on the distributed Performance Metrics Name Space (PMNS), however if the -n option is specified an alternative local PMNS is loaded from the file pmnsfile.

Under normal circumstances, pmlogger will run forever (except for a -s option or a termination signal). The -T option may be used to limit the execution time using the format of time as prescribed by PCPIntro(1). The time is interpreted within the time zone of the PMCD server, unless the -y option is given, within which case the time zone at this logger host is used. Some examples of different formats: -T 10mins -T '@ 11:30' From this it can be seen that -T 10mins and -s 10mins perform identical actions.

Alternatively, pmlogger runtime may be limited to the lifetime of another process by using the -p or --PID option to nominate the PID of the process of interest. In this case the pmlogger will exit when the other process no longer exists.

When pmlogger receives a SIGHUP signal, the current volume of the log is closed, and a new volume is opened. This mechanism (or the alternative mechanism via pmlc(1)) may be used to manage the growth of the log files - once a log volume is closed, that file may be archived without ill-effect on the continued operation of pmlogger. See also the -v option above.

When pmlogger receives a SIGUSR2 signal, the current archive log is closed, and a new archive is opened. For this to succeed, the original archive argument must include strftime(3) meta characters (e.g. %Y%m%d.%H.%M), otherwise pmlogger will exit because the archive files will already exist and pmlogger will not over-write existing archive files. Note that SIGUSR2 triggers pmlogger to re-exec itself and re-parse all original arguments. This means that any relative time limits placed on it's termination time or sampling limit are reset and begin again. This only affects relative termination times, not absolute times e.g. -T 5s is affected, but -T 5pm is not.

Historically the buffers for the current log may be flushed to disk using the flush command of pmlc(1), or by using the -u option. The current version of pmlogger and the libpcp routines that underpin pmlogger unconditionally use unbuffered writes and a single fwrite(3) for each logical record written, and so ``flushing'' does not force any additional data to be written to the file system. The -u option and the pmlc(1) flush command are retained for backwards compatibility.

When launched with the -x option, pmlogger will accept asynchronous control requests on the file descriptor fd. This option is only expected to be used internally by PCP applications that support ``live record mode''.

The -m option allows the string note to be appended to the map file for this instance of pmlogger in the $PCP_TMP_DIR/pmlogger directory. This is currently used internally to document the file descriptor (fd) when the -x option is used, or to indicate that this pmlogger instance was started under the control of pmlogger_check(1), (-m pmlogger_check) or was re-exec'd (see execvp(3)) due to a SIGUSR2 signal being recieved as described above (-m reexec).

The -H option allows the hostname written into the archive label to be overridden. This mirrors the -H option of pmcd(1) , but allows it to be specified on the pmlogger process. Without this option, the value returned from the logged pmcd(1) is used.

The -C option will cause the configuration file to be parsed and pmlogger will then exit without creating an output archive, so when -C is specified, the archive command line argument is not required. Any errors in the configuration file are reported.