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   pmda    ( 3 )

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NAMESPACE

Every PMDA has its own unique namespace using the format defined
       in PMNS(5).  In summary, the namespace matches the names of the
       metrics to the unique identifier.  The simple PMDA defines five
       metrics: simple.numfetch, simple.color, simple.time.user,
       simple.time.sys and simple.now.  The namespace for these metrics
       is defined in $PCP_PMDAS_DIR/simple/pmns and is installed as:

            simple {
                numfetch    253:0:0
                color       253:0:1
                time
                now         253:2:4
            }

            simple.time {
                user        253:1:2
                sys         253:1:3
            }

       The domain number of 253 is obtained from
       $PCP_VAR_DIR/pmns/stdpmid.  New PMDAs should specify a unique
       domain number in this file, and obtain the number during
       installation.  This allows the domain number to change by
       modifying only the file $PCP_VAR_DIR/pmns/stdpmid.

       The simple.time and simple.now metrics are defined in separate
       clusters to the other metrics which allows a PMDA to support more
       than 1024 metrics, as well as grouping similar metrics together.
       Therefore, the item numbers for a new cluster may be identical to
       the item numbers in other clusters.  The simple PMDA continues to
       increment the item numbers to permit direct mapping (see
       pmdaInit(3)).

       The namespace file should be installed and removed with the agent
       using pmnsadd(1) and pmnsdel(1).  See the later sections on
       INSTALLATION and REMOVAL.

       A simple ASCII namespace can be constructed by creating a file
       similar to $PCP_PMDAS_DIR/simple/root:

            /*
             * fake "root" for validating the local PMNS subtree
             */

            #include "$PCP_VAR_DIR/pmns/stdpmid"

            root { simple }

            #include "pmns"

       and can be referred to with the -n option in most PCP tools.