CentOS 7.0 - man page for pmdajbd2 (centos section 1)

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PMDAJBD2(1)									      PMDAJBD2(1)

NAME
       pmdajbd2 - journal block device (JBD) performance metrics domain agent (PMDA)

SYNOPSIS
       $PCP_PMDAS_DIR/jbd2/pmdajbd2 [-d domain] [-l logfile] [-j path] [-U username]

DESCRIPTION
       pmdajbd2  is  a Performance Metrics Domain Agent (PMDA) which extracts performance metrics
       from the Journal Block Device subsystem (version 2) in the Linux  kernel.   These  metrics
       are exported by the kernel in procfs files, one file per block device.  The JBD2 subsystem
       is used by several filesystems including ext3, ext4 and ocfs2.

       The jbd2 PMDA exports metrics that measure detailed journal transaction information,  such
       as time spent waiting and locked, request rates, blocks used and so on.

       A  brief description of the pmdajbd2 command line options follows (these are only relevant
       when running the PMDA as a daemon, and not as a shared library):

       -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, when running as a  daemon  a  log  file  named
	    jbd2.log  is  written  in  the  current  directory	of when pmdajbd2 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.  When running in shared library mode, and
	    diagnostic	information  will  be  written	 into	the   pmcd   log   file,   namely
	    $PCP_LOG_DIR/pmcd/pmcd.log.

       -j   Allows  an	alternate path to the jbd2 statistics files to be specified.  The default
	    path is /proc/fs/jbd2.

       -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
       This PMDA is installed by default and in the shared library mode (rather than as  a  sepa-
       rate  daemon  to pmcd(1)).  Thus, the names, help text and values for the jbd2 performance
       metrics should always be available.

       If you do not use these metrics you can remove this PMDA, do the following as root:

	    # cd $PCP_PMDAS_DIR/jbd2
	    # ./Remove

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

	    # cd $PCP_PMDAS_DIR/jbd2
	    # ./Install

       pmdajbd2 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 pmdajbd2
       $PCP_PMDAS_DIR/jbd2/help
		 default help text file for the jbd2 metrics
       $PCP_PMDAS_DIR/jbd2/Install
		 installation script for the pmdajbd2 agent
       $PCP_PMDAS_DIR/jbd2/Remove
		 undo installation script for the pmdajbd2 agent
       $PCP_LOG_DIR/pmcd/jbd2.log
		 default log file for error messages and other information from pmdajbd2

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 config-
       uration file, as described in pcp.conf(5).

SEE ALSO
       PCPIntro(1), pmcd(1), pcp.conf(5) and pcp.env(5).

Performance Co-Pilot			       PCP				      PMDAJBD2(1)
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