NAME
pmnewlog - stop and restart archive logging for PCP performance metrics
SYNOPSIS
$PCP_BINADM_DIR/pmnewlog [-a accessfile] [-C saveconfig] [-c
configfile] [-N] [-n pmnsfile] [-P] [-p pid] [-s] [-V] [other pmlogger
options] archive
DESCRIPTION
pmnewlog may be used to stop and restart a running instance of
pmlogger(1). This is most useful for managing multiple sets of
Performance Co-Pilot (PCP) archive logs. These archive logs record the
history of performance metric values that may be ‘‘played back’’ by
other PCP tools, and they form the basis of the VCR paradigm and
retrospective performance analysis services common to the PCP toolkit.
In normal usage, pmnewlog would be executed by cron(1) in the wee hours
to terminate one PCP archive log and start another, i.e. to perform log
rotation.
Even more common, would be the execution of pmnewlog from the PCP
archive management script pmlogger_daily(1). In this case, direct end-
user execution of pmnewlog is most unlikely.
The mandatory argument archive is the base name for the physical files
that will constitute the new archive log.
The pmlogger instance to be stopped and restarted must be running on
the same system as pmnewlog and is either the primary logger (the
default) or the logger with pid as specified by the -p option.
If the -n option is specified, then pmnewlog will use the namespace in
the pmnsfile, rather than the default Performance Metrics Name Space
(PMNS).
If no -c option is specified, pmnewlog will use pmlc(1) to connect to
the running pmlogger(1) and so determine all those metrics and
instances that are subject to mandatory logging or advisory on logging,
and the associated logging frequencies. This information is used to
synthesize a new pmlogger(1) configuration file. If the -n option is
specified, it will also be used for these interactions with pmlc(1).
If the -c option is specified, pmlogger(1) will be restarted with
configfile as the configuration file. Normally configfile would be the
same configuration file used to start pmlogger(1) in the first place,
however note that since pmlogger(1) is restarted, any changes to the
logging status made using pmlc(1) will be lost, unless these have also
been reflected in changes to configfile.
If configfile does not exist, then a search is made in the directory
$PCP_VAR_DIR/config/pmlogger for a file of the same name, and if found
that file is used, e.g. if config.mumble does not exist in the current
directory and the file $PCP_VAR_DIR/config/pmlogger/config.mumble does
exist, then -c config.mumble and -c
$PCP_VAR_DIR/config/pmlogger/config.mumble are equivalent.
Access controls specifications for the new pmlogger(1) instance may
optionally be provided via the -a option. The contents of accessfile
should start with the literal token [access] and conform to the syntax
of the access controls section as described for pmlogger(1).
The -C option may be used to save the configuration file that pmnewlog
passes to the newly launched pmlogger(1).
If the pmlogger(1) instance needs to be started under the control of
pmsocks(1) to connect to a pmcd through a firewall, the -s option may
be used.
The -V option enables verbose reporting of the activity. By default no
output is generated unless some error or warning condition is
encountered.
The -N option enables a ‘‘show me’’ mode, where the actions are echoed,
but not executed, in the style of ‘‘make -n’’. Using -N in conjunction
with -V maximizes the diagnostic capabilities for debugging.
The other pmlogger options are as described for pmlogger(1). Note that
pmnewlog does not support the following options of pmlogger(1).
-h host
pmnewlog determines the host to which the new pmlogger(1) should
connect based upon the current host connection for the old
pmlogger(1).
-s samples
The new pmlogger(1) is expected to be long running, and the -s
option of pmnewlog takes precedence.
-T runtime
The new pmlogger(1) is expected to be long running
-V version
The new pmlogger will always create the latest version PCP
archive format, and the -V option of pmnewlog takes precedence.
-x fd The launched pmlogger cannot be controlled by
pmRecordControl(3).
EXAMPLE
The following sh(1) script could be executed by root via cron(1) to
start a new set of archive logs for the primary logger each evening. A
more complete version of this script may be found in
$PCP_BINADM_DIR/pmlogger_daily, and is documented in the manual page
for pmlogger_daily(1).
#!/bin/sh
# start new logs for PCP primary logger on this host
# standard place for logs
LOGDIR=$PCP_LOG_DIR/pmlogger/‘hostname‘
# each new log is named yymmdd.hh.mm
LOGNAME=‘date "+%Y%m%d.%H.%M"‘
# do it
[ ! -d $LOGDIR ] && mkdir -p $LOGDIR
cd $LOGDIR
$PCP_BINADM_DIR/pmnewlog -l $LOGDIR/pmlogger.log $LOGDIR
FILES
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_BINADM_DIR/pmlogger_daily
sample script to rotate archives for a number of loggers
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(4).
SEE ALSO
PCPIntro(1), pmcd(1), pmdumplog(1), pmlc(1), pmlogger(1),
pmlogger_daily(1), pmsocks(1), pcp.conf(4) and pcp.env(4).
DIAGNOSTICS
Due to the precious nature of the archive logs, pmnewlog is rather
paranoid in its checking and validation, and will try very hard to
ensure that an appropriately configured pmlogger(1) can be restarted,
before terminating the existing pmlogger(1).
As a consequence of this checking, pmnewlog tends to generate rather
verbose error and warning messages.
CAVEATS
If no configfile is specified, the method for synthesizing a
configuration file using a pmlc(1) connection to the existing
pmlogger(1) is, of necessity, incomplete. In particular, for metrics
with dynamic underlying instance domains, it is not possible to
identify a configuration that logs all instances of a metric all of the
time, so rather the synthesized configuration file requests the
continued logging of the set of instances that exist at the time
pmlogger(1) is interrogated by pmnewlog.
If this situation is a concern, a fixed configuration file should be
used, and passed to pmnewlog via the -c option.