e X treme DB High Availability is a fault-tolerant version of the e X treme DB(TM) in-memory embedded database. Designed for systems that cannot afford to fail, e X treme DB HA delivers the highest degree of reliability, along with its unsurpassed performance and exceptionally small footprint. Process control, telecom and network gear, and other embedded systems with demanding--“five-nines ” reliability (99.999% up-time) requirements comprise a fast-growing segment of real-time applications. These systems are managing greater volumes of more complex data--creating a need for a fast, lightweight commercial off-the-shelf (COTS) high availability database that can meet their reliability imperative. Typically, existing fault-tolerant systems use replication schemes to create backup embedded database copies. But replication entails latency from the moment a primary data store is updated, until these changes are propagated to the replica database. Such latency is often unacceptable in time-critical embedded systems. The e X treme DB HA runtime maintains multiple identical embedded database instances within separate address spaces. Typical hardware configurations include: Multiple processes or threads within the same hardware instance Two or more boards in a chassis with a high-speed bus for communication Separate address spaces on boards connected via industry standard communication media and protocol such as RS-485/RS-232, Control Area Network (CAN) or Ethernet Two or more controllers connected via a proprietary communication media and/or protocol Separate computers on a LAN e X treme DB HA is based on a rugged, time-cognizant two-phase commit protocol that ensures changes to the main instance database and identical standby instances succeed or fail together. A High Availability control interface exported by the e X treme DB HA runtime provides the means for the application to configure, establish, maintain and terminate e X treme DB HA connections. A time cognizant HA transport protocol enables communication as well as detection of timeout situations.