In replicated database systems, a replication control protocol is needed to ensure one-copy serializability. The author incorporates the concept of a regeneration into the missing-partition dynamic voting scheme to design a replication control protocol. Like the original missing-partition dynamic voting scheme, this protocol supports an inexpensive read operation which accesses one copy, rather than all copies, of each data item read. By incorporating the concept of regeneration and keeping multiple versions for each data item in the database, higher data availability is maintained. To support data regeneration, a replicated directory architecture for the proposed replication control protocol is designed, and it not only supports regeneration of replicated data items, but also provides inexpensive, high-availability directory services, which help maintain database availability.>

A replication control protocol utilizing dynamic voting is presented for ensuring database correctness so that the system behaves like a one-copy database to the users. The protocol dynamically adjusts vote assignment of data items in response to failures and recoveries, thus maintaining higher data availability than static voting schemes in the event of network partitioning. Unlike existing dynamic voting schemes, it supports inexpensive read operations which access one copy, rather than all copies, of each data item read. Since read operations outnumber write operations in most applications, this protocol enjoys better performance. With this protocol, transactions run in one of three modes: normal mode, missing-partition mode, or pseudo-normal mode. Because a partition number and a last current copy cardinality are associated with each copy, read operations only require one copy of a data item when run in the normal mode.>

A quorum-based commit and termination protocol is designed with the goal of maintaining high data availability in case of failures. The protocol proposed is resilient to arbitrary concurrent site failures, lost messages, and network partitioning. The major difference between this protocol and existing ones is that the voting partition processing strategy is taken into consideration in the design. As a result, the protocol is expected to maintain higher data availability.>

Resilient commit protocols for multisite simple network partitioning are studied in this paper. The necessity of termination protocols to make commit protocols resilient in multisite simple network partitioning is presented. A termination protocol that makes the three-phase commit protocol resilient is designed. This protocol is valid even for transient network partitioning. The method can be generalized to design termination protocols for other commit protocols in multisite simple network partitioning.