pmlogger_daily is intended to be run once per day, preferably in the early morning, as soon after midnight as practicable. Its task is to aggregate, rotate and perform general housekeeping one or more sets of PCP archives.
After some period, old PCP archives are discarded. This period is 14 days by default, but may be changed using the -k option. Some special values are recognized for the period ( discard ), namely 0 to keep no archives beyond the current one, and forever or never to prevent any archives being discarded. Note that the semantics of discard are that it is measured from the time of last modification of each archive, and not from the current day. This has subtle implications for compression (see below) - the compression process results in the creation of new archive files which have new modification times. In this case, the discard period (re)starts from the time of compression.
Archive data files can optionally be compressed after some period to conserve disk space. This is particularly useful for large numbers of pmlogger processes under the control of pmlogger_check . If transparent_decompress is enabled when libpcp was built (can be checked with pmconfig -L ), then the default behaviour is compression ``as soon as possible'' otherwise the default behaviour is to not compress files (which matches the historical default behaviour in earlier PCP releases).
The -x option controls compression and compress specifies the number of days after which to compress archive data files and metadata files. If compress is 0 then compression will be applied as soon as possible. If compress is never or forever then no compression will be done. The environment variable PCP_COMPRESSAFTER may be used as an alternative mechanism to define compress . If both PCP_COMPRESSAFTER and -x specify different values for compress then the environment variable value is used and a warning is issued.
The -X option specifies the program to use for compression - by default this is xz (1). The environment variable PCP_COMPRESS may be used as an alternative mechanism to define program . If both PCP_COMPRESS and -X specify different compression programs then the environment variable value is used and a warning is issued.
Use of the -Y option allows a regular expression to be specified causing files in the set of files matched for compression to be omitted - this allows only the data file to be compressed, and also prevents the program from attempting to compress it more than once. The default regex is ".(index|Z|gz|bz2|zip|xz|lzma|lzo|lz4)$" - such files are filtered using the -v option to egrep (1). The environment variable PCP_COMPRESSREGEX may be used as an alternative mechanism to define regex . If both PCP_COMPRESSREGEX and -Y specify different values for regex then the environment variable value is used and a warning is issued.
To accommodate the evolution of PMDAs and changes in production logging environments, pmlogger_daily is integrated with pmlogrewrite (1) to allow optional and automatic rewriting of archives before merging. If there are global rewriting rules to be applied across all archives mentioned in the control file(s), then create the directory $PCP_SYSCONF_DIR/pmlogrewrite and place any pmlogrewrite (1) rewriting rules in this directory. For rewriting rules that are specific to only one family of archives, use the directory name from the control file(s) - i.e. the fourth field - and create a file, or a directory, or a symbolic link named pmlogrewrite within this directory and place the required rewriting rule(s) in the pmlogrewrite file or in files within the pmlogrewrite subdirectory. pmlogger_daily will choose rewriting rules from the archive directory if they exist, else rewriting rules from $PCP_SYSCONF_DIR/pmlogrewrite if that directory exists, else no rewriting is attempted.
The -r command line option acts as an over-ride and prevents all archive rewriting with pmlogrewrite (1) independent of the presence of any rewriting rule files or directories.
Sometimes PMDA changes require all archives to be rewritten, not just the ones involved in any current merging. This is required for example after a PCP upgrade where a new version of an existing PMDA has revised metadata. The -R command line forces this universal-style of rewriting.
The -R option to pmlogger_daily is mutually exclusive with both the -r and -M options.
As an alternate mechanism, if the file $PCP_LOG_DIR/pmlogger/.NeedRewrite exists when pmlogger_daily starts then this is treated the same as specifying -R on the command line and $PCP_LOG_DIR/pmlogger/.NeedRewrite will be removed once all the rewriting has been done.
By default all possible archives will be merged. The -o option reinstates the old behaviour in which only yesterday's archives will be considered as merge candidates.
In the special case where only a single input archive needs to be merged, pmlogmv (1) is used to rename the archive, otherwise pmlogger_merge (1) is used to merge all of the archives for a single host and a single day into a new PCP archive and the individual archives are removed.
The -M option may be used to disable archive merging (or renaming) and rewriting ( -M implies -r ). This is most useful in cases where the archives are being incrementally copied to a remote repository, e.g. using rsync (1). Merging, renaming and rewriting all risk an increase in the synchronization load, especially immediately after pmlogger_daily has run, so -M may be useful in these cases.
To assist with debugging or diagnosing intermittent failures the -t option may be used. This will turn on very verbose tracing ( -VV ) and capture the trace output in a file named $PCP_LOG_DIR/pmlogger/daily. datestamp .trace, where datestamp is the time pmlogger_daily was run in the format YYYYMMDD.HH.MM. In addition, the want argument will ensure that trace files created with -t will be kept for want days and then discarded.
In addition, if the PCP ``notices'' file ( $PCP_LOG_DIR/NOTICES ) is larger than 20480 bytes, pmlogger_daily will rename the file with a ``.old'' suffix, and start a new ``notices'' file. The rotate threshold may be changed from 20480 to size bytes using the -s option.
Use of the -m option causes pmlogger_daily to construct a summary of the ``notices'' file entries which were generated in the last 24 hours, and e-mail that summary to the set of space-separated addresses . This daily summary is stored in the file $PCP_LOG_DIR/NOTICES.daily , which will be empty when no new ``notices'' entries were made in the previous 24 hour period.
If the -K option is specified for pmlogger_daily then only the compression tasks are attempted, so no pmlogger (1) rotation, no culling, no rewriting, etc. When -K is used and a compress value of 0 is in effect (from -x on the command line or PCP_COMPRESSAFTER in the environment or via the control file) this is intended for environments where compression of archives is desired before the scheduled daily processing happens. To achieve this, once pmlogger_check has completed regular processing, it calls pmlogger_daily with just the -K option. Provided PCP_COMPRESSAFTER is set to 0 along with any other required compression options to match the scheduled invocation of pmlogger_daily , then this will compress all volumes except the ones being currently written by pmlogger (1).
If the -p option is specified for pmlogger_daily then the status of the daily processing is polled and if the daily pmlogger (1) rotation, culling, rewriting, compressing, etc. has not been done in the last 24 hours then it is done now. The intent is to have pmlogger_daily called regularly with the -p option (at 30 mins past the hour, every hour in the default cron (8) set up) to ensure daily processing happens as soon as possible if it was missed at the regularly scheduled time (which is 00:10 by default), e.g. if the system was down or suspended at that time.
With the -p option, pmlogger_daily simply exits if the previous day's processing has already been done.
The -K and -p options to pmlogger_daily are mutually exclusive.
The script $PCP_BINADM_DIR/pmlogger_daily could be copied and modified to implement a site-specific procedure for end-of-week and/or end-of-month management for a set of PCP archives.
pmlogger_check may be run at any time, and is intended to check that the desired set of pmlogger (1) processes are running, and if not to re-launch any failed loggers. Use of the -s option provides the reverse functionality, allowing the set of pmlogger processes to be cleanly shutdown. Use of the -C option queries the system service runlevel information for pmlogger , and uses that to determine whether to start processes.
The -T option provides a terser form of output for pmlogger_check that is most suitable for a pmlogger ``farm'' where many instances of pmlogger are expected to be running.
Using -N option invokes the scripts in a ``show me'' or ``dry run'' mode where the tasks that would be performed are reported, but no changes are made. This is typically used for debugging in combination with one (verbose) or two (very verbose) -V options.
Both pmlogger_daily and pmlogger_check are controlled by PCP logger control file(s) that specifies the pmlogger instances to be managed. The default control file is $PCP_PMLOGGERCONTROL_PATH , but an alternate may be specified using the -c option. If the directory $PCP_PMLOGGERCONTROL_PATH .d (or control .d from the -c option) exists, then the contents of any additional control files therein will be appended to the main control file (which must exist).
Warning : The $PCP_PMLOGGERCONTROL_PATH and $PCP_PMLOGGERCONTROL_PATH .d files must not be writable by any user other than root.
The control file(s) should be customized according to the following rules that define for the current version (1.1) of the control file format.
host y|n y|n directory args
The following sample control lines specify a primary logger on the local host ( bozo ), and non-primary loggers to collect and log performance metrics from the hosts wobbly and boing .
$version=1.1 bozo y n $PCP_LOG_DIR/pmlogger/bozo -c config.default wobbly n n "/store/wobbly/$(date +%Y)" -c ./wobbly.config boing n n $PCP_LOG_DIR/pmlogger/boing -c ./pmlogger.config
Typical crontab (5) entries for periodic execution of pmlogger_daily and pmlogger_check are given in $PCP_SYSCONF_DIR/pmlogger/crontab (unless installed by default in /etc/cron.d already) and shown below.
# daily processing of archive logs 14 0 * * * $PCP_BINADM_DIR/pmlogger_daily # every 30 minutes, check pmlogger instances are running 25,55 * * * * $PCP_BINADM_DIR/pmlogger_check
In order to ensure that mail is not unintentionally sent when these scripts are run from cron (8) diagnostics are always sent to a log file. By default, this file is $PCP_LOG_DIR/pmlogger/pmlogger_daily.log or $PCP_LOG_DIR/pmlogger/pmlogger_check.log but this can be changed using the -l option. If this log file already exists when the script starts, it will be renamed with a .prev suffix (overwriting any log file saved earlier) before diagnostics are generated to the log file. The -l and -t options cannot be used together.
The output from the cron execution of the scripts may be extended using the -V option to the scripts which will enable verbose tracing of their activity. By default the scripts generate no output unless some error or warning condition is encountered.