When a cluster system boots, the kernel drivers and VCS process start in a particular order. If it is the first system in the cluster, VCS reads the cluster configuration file main.cf and builds an in-memory configuration database. This is the LOCAL_BUILD state. After building the configuration database, the system transitions into the RUNNING mode. If another system joins the cluster while the first system is in the LOCAL_BUILD state, it must wait until the first system transitions into RUNNING mode. The time it takes to build the configuration depends on the number of service groups in the configuration and their dependencies, and the number of resources per group and resource dependencies. VCS creates an object for each system, service group, type, and resource. Typically, the number of systems, service groups and types are few, so the number of resources and resource dependencies determine how long it takes to build the configuration database and get VCS into RUNNING mode. If a system joins a cluster in which at least one system is in RUNNING mode, it builds the configuration from the lowest-numbered system in that mode.