6. DATA SOURCES › 6.2 Processing Network Monitor Data From VM Hosts › 6.2.1 Tivoli NetView Performance Monitor (NPM) › 6.2.1.2 NPM Session Collection Function

6.2.1.2 NPM Session Collection Function

The NPM session collection function gathers response time and
load data at its VTAM interface.  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 collection function can record
response time and load data to the NPM SMF type 28 record (or
the VM equivalent), as well as to the Session Statistics
File, a key-sequenced VSAM file.

The NPM session data can be input to CA MICS only in SMF
format or the VM equivalent (type 28 record, subtype '20'X).
Modify the DAY056 step of the CA MICS DAILY operational job
following the instructions in section 7.3.2 of this guide to
process this data.

CONTROLLING THE VOLUME OF DATA
------------------------------

The NPM session collection 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.

More information is provided in Chapter 9, Operational
Considerations.

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 the data center's responsibility to activate DR for
any transactions that require network response time.