EMS Manual

Configuring EMS
EMS Manual—426909-005
12-19
Delivery Integrity
collector cannot then keep up with the peak logging demand. Setting
BLOCKING to ON increases the maximum sustained logging rate of the
primary and alternate collectors by a factor of two.)

Verify that subsystems are generating only the event messages they are
supposed to generate (for example, check that no subsystem is in a loop).

Verify that the filters used by forwarding distributors are selecting only the
desired event messages.

At the next system load, enlarge the buffer for the primary collector by
increasing the number of pages of resident extended memory that the
collector can use. (For a description of how to enlarge the buffer size, see
Installation and System Generation Considerations on page 12-21.)

The next time the alternate collector is started, enlarge the buffer for the
collector by increasing the value of the POOLPAGES attribute.
The status information returned by a collector—in response to a STATUS command
message or to the interactive EMSCINFO program—includes the current collector
attribute settings, as well as statistics indicating the number of event messages
received, logged, and discarded due to flooding.
Delivery Integrity
Event-message delivery can continue in many cases where logging is impossible; for
example, where log-file space is inadequate. In such cases, a collector queues
messages in memory and delivers them directly to the appropriate distributors.
Appropriate distributors are the compatibility distributor and other distributors
(consumer, forwarding, or printing) that retrieve event messages as the collector
receives them.
After log-file access is restored, a collector logs the queued event messages and
restores message delivery from direct delivery to normal delivery. All messages are
logged if logging resumes before queue space is exhausted. Otherwise, the collector
must discard some of the newest messages.
Performance
Collector performance is determined primarily by the log-file considerations in Logging
Integrity on page 12-17. For all other EMS processes (and, to a lesser extent, for
collectors as well), the most significant performance issue is filter effectiveness. Filters
that select the exact set of event messages required (no fewer and no more) let all
event-message collectors, distributors, and their destinations function more efficiently.
For guidelines on creating efficient filters, see The Filter Language
on page 5-7, and
Section 6, Filter Tables and Burst Filters. Blocking is also significant because it can
double the rate of message logging.