This it not handled directly by ExpressID AFIS Cluster (Eafis). This has to be configured on DB side. Every enterprise SQL DB engine supports kind of high-availability mode (e.g., Oracle has Oracle RAC). After you have available running DB HA cluster, correct connection string has to be set in Eafis's config.xml. It depends on particular DB whether there is one cluster's IP address or multiple addresses in JDBC connection string. The connection to DB HA cluster from Eafis is handled by DB's jdbc client driver, represented by jar file, which is part of Eafis.