PMDAMMV(1)						      General Commands Manual							PMDAMMV(1)

NAME

       pmdammv - memory mapped values performance metrics domain agent (PMDA)

SYNOPSIS

       $PCP_PMDAS_DIR/mmv/pmdammv [-d domain] [-l logfile] [-U username]

DESCRIPTION

       pmdammv	is  a  Performance  Metrics Domain Agent (PMDA) which exports application level performance metrics using memory mapped files.	It
       offers an extremely low overhead instrumentation facility that is well-suited to long running, mission critical applications  where  it	is
       desirable to have performance metrics and availability information permanently enabled.

       The  mmv  PMDA  exports instrumentation that has been added to an application using the MMV APIs (refer to mmv_stats_init(3) and mmv(5) for
       further details).  These APIs can be called from several languages, including C, C++, Perl, Python and Java (via the  separate  ``Parfait''
       class library).

       A brief description of the pmdammv command line options follows:

       -d   It	is  absolutely crucial that the performance metrics domain number specified here is unique and consistent.  That is, domain should
	    be different for every PMDA on the one host, and the same domain number should be used for the same PMDA on all hosts.

       -l   Location of the log file.  By default, a log file named mmv.log is written in  the	current  directory  of	pmcd(1)  when  pmdammv	is
	    started,  i.e.   $PCP_LOG_DIR/pmcd.   If  the  log	file cannot be created or is not writable, output is written to the standard error
	    instead.

       -U   User account under which to run the agent.	The default is the unprivileged "pcp" account in current versions of  PCP,  but  in  older
	    versions the superuser account ("root") was used by default.

INSTALLATION

       If you want access to the names, help text and values for the mmv performance metrics, do the following as root:

	    # cd $PCP_PMDAS_DIR/mmv
	    # ./Install

       Note  that  the default mechanism for sharing memory mapped values between instrumented applications and the mmv PMDA involves the creation
       of a world-writeable $PCP_TMP_DIR/mmv directory with the sticky-bit set (similar to /tmp and /var/tmp,  for  example).	This  suffices	to
       allow  any application, running under any user account, to communicate with the PMDA (which runs under the "pcp" account by default).  This
       may not be desirable for every environment, and one should consider the security implications of any directory  setup  like  this  (similar
       classes of issues exist as those that affect the system temporary file directories).

       The installation process will not overwrite any existing $PCP_TMP_DIR/mmv directory.  Thus it is possible to implement an alternate permis-
       sions strategy with no world-writable directory for sharing files - any directory readable by user or group "pcp" will suffice.

       If you want to undo the installation, do the following as root:

	    # cd $PCP_PMDAS_DIR/mmv
	    # ./Remove

       pmdammv is launched by pmcd(1) and should never be executed directly.  The Install and Remove scripts notify  pmcd(1)  when  the  agent	is
       installed or removed.

FILES

       $PCP_PMCDCONF_PATH
		 command line options used to launch pmdammv
       $PCP_TMP_DIR/mmv
		 directory housing memory mapped value files
       $PCP_PMDAS_DIR/mmv/help
		 default help text file for the mmv metrics
       $PCP_PMDAS_DIR/mmv/Install
		 installation script for the pmdammv agent
       $PCP_PMDAS_DIR/mmv/Remove
		 undo installation script for the pmdammv agent
       $PCP_LOG_DIR/pmcd/mmv.log
		 default log file for error messages and other information from pmdammv

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	configura-
       tion file, as described in pcp.conf(5).

SEE ALSO

       PCPIntro(1), pmcd(1), mmv_stats_init(3), mmv(5), pcp.conf(5) and pcp.env(5).

Performance Co-Pilot							PCP								PMDAMMV(1)