Analysis of two-level information system with data replication

Distributed information system (IS) is considered with main (central) database (MDB) and collection of local databases (LDBs) at remote user workstations. With the help of asynchronous replication mechanisms a copy of certain part of MDB is maintained in each LDB. Mathematical model for analyzed system is presented and by means of this model it is demonstrated that under certain conditions the presence of local data decreases the mean duration of query processing and reduces as well expenses for data transmission between separate elements of IS.