Missing Performance Statistics in Performance Graphs

1. Rebuild the database indexes to eliminate the fragmentation.
   
   
2. Ensure that the system the database server is running on is not overloaded, busy, and does not have insufficient memory. Overloaded or busy systems can affect the database performance.
   
   
3. Ensure that the CPU usage for the system the database server is running on is not always at a high level. CPU usage at a constant high level indicates the database server is overloaded or that there is some problem with the system.
   
   
4. Use the database that is appropriate to your environment. If you are using Microsoft Access for the VirtualCenter database and you have several hosts and virtual machines, consider migrating your database to a more robust platform, such as the supported Microsoft SQL or Oracle databases. This will improve database performance.
   
   
5. Ensure the network traffic between the VirtualCenter server and the VirtualCenter database server is not overloaded. Overly busy network traffic causes data transfer delays between the two servers.

If the performance graphs show gaps only on specific hosts, it is likely that there are problems with these particular hosts or communication between hosts and VirtualCenter server. Occasionally, ccagent can be busy or blocked during a time when it is supposed to retrieve statistical data, preventing it from collecting the data on time. Check the following items to ensure ccagent is performing correctly.

1. Verify NIS+ does not have any performance problems. Slow NIS causes delays in retrieving user and group information, which results in delays for other ccagent operations.
   
   
2. Verify there are not I/O problems, which might block the ccagent.