6. DATA SOURCES › 6.1 Data Sources Overview › 6.1.1 NetView Performance Monitor (NPM) › 6.1.1.2 NPM Session Collector Function

6.1.1.2 NPM Session Collector Function

NPM Session Collector Function gathers response time and
loads data at its VTAM interface.  Once there, NPM intercepts
the VTAM buffer trace module and saves information from the
buffer trace in CSA until the session collection interval
expires.  At this point, the data in CSA is assembled and
recorded.  The NPM Session Collector Function records
response time and loads data to the NPM SMF type 28 record,
as well as to the Session Statistics File, which is a
key-sequenced VSAM file.  NPM session data can be input to CA
MICS network only in SMF format.

For VM, NPM Session Collector Function records response time
and loads data in SMF type 28, subtype '20'X.  It is also
your responsibility to transport the VM SMF-equivalent type
28 records to your CA MICS MVS host.  No special preparation
is required.

Controlling the Volume of Data
------------------------------
The NPM Session Collector Function initiates a VTAM buffer
trace for each resource requested by the Session Collection
command.  As a result, CSA storage and direct access storage
space that is needed to contain this data for all logical
units (LUs) on a medium-to-large network is prohibitive.
Therefore, NPM provides the data center with the ability to
record data for selected network components only.  You can
use both the SESSCOLL command, which is invoked at NPM
initialization, and the Start Session Collection screen to
limit the data to specific LUs.  You can also choose to
specify all LUs that are associated with specific nodes
(including local NCPs, cross-domain NCPs, local hosts, and
cross-domain hosts), applications, or virtual routes.

Network Response Time and Definite Response
-------------------------------------------
NPM's network response time (transit time in NPM terms) is an
approximation of the time each transaction spends in the
network.  It is only measured by the NPM session collection
function for transactions that specify definite response
(DR).

It is your responsibility to activate DR for any transactions
that require network response time.