1. Does the problem seem to be caused by or related to the monitoring agent?

Note: Avoid a basic problem with OMEGAMON® for Storage on z/OS® by understanding the basic product architecture, as described here. The OMEGAMON for Storage on z/OS monitoring agent must report to a local Tivoli® Enterprise Monitoring Server that is installed and configured in the same z/OS address space. The local server for each agent must report to a hub server. The hub server can be running on any supported system. (If located in a z/OS system, the hub server can also act as the local server for a specific monitoring agent.)
Your answer: Do this next:
No Refer to IBM® Tivoli Monitoring Troubleshooting Guide. This document helps you resolve problems beyond a specific monitoring agent, such as problems with the Tivoli Enterprise Portal and problems with historical reporting.
Yes Go to Step 2. Has required maintenance been applied?.

Do not worry if you cannot answer this question with certainty at this stage. Later in this process, you generate trace logs that can pinpoint the source of a problem.