VCS performance consideration when a resource comes online

The online function of an agent brings the resource online. This function may return before the resource is fully online. The subsequent monitor determines if the resource is online, then reports that information to VCS. The time it takes to bring a resource online equals the time for the resource to go online, plus the time for the subsequent monitor to execute and report to VCS.

Most resources are online when the online function finishes. The agent schedules the monitor immediately after the function finishes, so the first monitor detects the resource as online. However, for some resources, such as a database server, recovery can take longer. In this case, the time it takes to bring a resource online depends on the amount of data to recover. It may take multiple monitor intervals before a database server is reported online. When this occurs, it is important to have the correct values configured for the OnlineTimeout and OnlineWaitLimit attributes of the database server resource type.