Parent Siblings Oriented Tree Quorum Protocol

In this paper, the authors are proposing a new replica control algorithm Parent Siblings Oriented Tree Quorum Protocol (PSTQ) for the management of replicated data in distributed database system. This algorithm imposes a logical structure of tree on the set of copies of an object. The proposed protocol provides a small read quorum as well as a small write quorum while guaranteeing fault-tolerance of write operations. With this algorithm read operation is executed by reading one copy in failure-free environment. In case of failure of sites, number of data copies required for read operation increases but remains constant for subsequent failure of the sites.