Patent ID: 6189017
Filing Date: 2001-02-13
Classification: G06F,Y10S

Abstract:
A method of ensuring the reliability of a distributed data base, that is distributed in a system, comprising; several computers which together form nodes wherein information belonging to said distributed data base can be stored, where a fragment comprises a part of said data base and includes a primary replica of said part, a secondary replica of said part, and a stand-by replica of said part, where said primary replica is stored within a first node, said secondary replica is stored within a second node that is separate from said first node, and said stand-by replica is stored within a third node that is separate from said first and said second nodes, where respective nodes include one or more primary, secondary and/or stand-by replicas of different fragments, where some transactions within the data base are changing transactions that result in changes in said fragment, which changes are performed in said primary replica, where said secondary replica and said stand-by replica are updated accordingly, where both data information and log information are stored within both said primary replica and said secondary replica, and where said secondary replica is used to re-create a primary replica should said first node crash, wherein said stand-by replica comprises only log information.