The session and policy binding databases are partitioned such that each server group in a Session or Binding resource domain hosts a portion of the data. Because each server group consists of redundant servers (Active/Standby, Active/Spare, or Active/Standby/Spare), the data owned by each Server Group is redundant within the Server Group.
Active, Standby, and Spare servers within a SBR server group all maintain exact replicas of the data for the partition for which the server group is responsible. This data is kept in sync by using a form of signaling called replication. The synchronized tables on the Standby and Spare servers are continually audited and updated to match the master copy on the Active server.
Figure 1 illustrates how a given Policy Binding table might be partitioned across four SBR Server Groups in a Policy Binding resource domain.
Figure 2 illustrates how each SBR Server Group hosts a partition of several tables. Only the Active server within each server group can write to the database. The Standby and Spare servers replicate only actions (adds, changes, and deletes) performed by the Active server.
