Optimal Termination Protocols for Network Partitioning

We address the problem of maintaining the distributed database consistency in presence of failures while maximizing the database availability. Network partitioning is a failure which partitions the distributed system into a number of parts, no part being able to communicate with any other. Formalizations of various notions in this context are developed and two measures for the performances of protocols in presence of a network partitioning are introduced. A general optimality theory is developed for two classes of protocols - centralized and decentralized. Optimal protocols are produced in all cases.published_or_final_versio

OPTIMAL TERMINATION PROTOCOLS FOR NETWORK PARTITIONING.

Commit protocols guarantee the consistency of distributed databases in absence of any failures. A commit protocol is resilient to a class of failures if it is possible to guarantee that a) databases at all operational sites in presence of these failures are consistent and b) other sites can be recovered consistently with these sites when the failure is repaired. It is proved that quorum-based termination protocols perform very well in the presence of network partitioning. If the central site is reliable, we can prove that centralized commit protocols indeed perform better than all decentralized ones. Thus, the general preference for centralized commit protocols is justified.link_to_subscribed_fulltex

INFORMATION-BASED MODEL FOR FAILURE-HANDLING IN DISTRIBUTED DATABASE SYSTEMS.

The authors consider the failure atomicity problem of distributed transactions in conjunction with the maximization of database availability. They propose a new information-based model for the distributed transaction execution, which explicitly expresses the information at each stage during a protocol. In addition to rederiving certain existing results. They prove a fundamental relation among the site failures and the network partitioning. The authors also propose a realistic model for site failures under which it is shown that the costs of commit and termination protocols can be greatly reduced. Finally, they explore the possible recovery strategies for a failed site and show how these are improved under their site failure model.link_to_subscribed_fulltex