Chapter 5. Optimizing performance within an IBM Tivoli Monitoring environment 179
number of attribute groups have been designated for historical collection
multiplied by the data collection interval.
After a PDS becomes full, the automatic maintenance process begins. A check is
made to see if there are any empty PDSs remaining to continue data collection. If
no empty data sets remain, then data collection is temporarily suspended while
maintenance is applied to the oldest data set.
The maintenance job will either back up the PDS to another location (such as
DASD or tape), or it will export the data into a flat file suitable for external
programs to post process the data. The maintenance job carries a large
overhead and if started will slow the entire historical collection process down.
We recommend that application of the maintenance jobs should be minimized.
For most users, the Tivoli Data Warehouse via the warehouse proxy agent
should be used as the backup procedure, rather than archiving onto tape or
DASD with a recommended warehousing occurring every 24 hours.
If the maintenance job is found to be running several times within a single
24-hour period due to the PDS becoming full, it is strongly recommended that the
PDS size should be increased until the job runs no more than once in any
24-hour period.
5.6.4 Tuning ITMS:Engine
The ITMS:Engine provides common functions such as communications,
diagnosis (dumps), and logging (RKLVLOG) for z/OS-based monitoring agents,
OMEGAMON II components of OMEGAMON XE products, plus z/OS-based
monitoring server. It has startup parameters defined with appropriate defaults for
most customer environments though for some customers with large amounts of
data to be transferred these defaults may be insufficient.
These parameters are defined in the data set pointed to by the RKLVIN DD
statement in the started task procedure for the monitoring agent or monitoring
server. Typically this would be as follows, where xx is replaced by the product
code for the monitoring agent or monitoring server:
If you find a message similar to Example 5-3 on page 180 in the RKLVLOG for an
OMEGAMON agent, it means an error has occurred when a monitoring agent
tried to return data for the table specified by the table variable and failed. The
most common cause of this error is a query that returns a large number of rows
of data, causing an out-of-memory condition.

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