Improved Reliability:In a centralised DBMS, a server failure stops the operations of the DBMS. Though, a failure at single site of a DDBMS, or a failure of a communication link creation some sites inaccessible, does not make the whole system inoperable. Distributed DBMSs are designed to continue to function despite such as failures. In particular, if data are replicated in various sites, a transaction requiring a particular data item may find it at various sites. Therefore, the failure of a site does not necessarily imply the shutdown of the system.
The failure of one site must be identified by the system, and appropriate action may be required to recover from the failure. The system has no longer used the services of the failed site. At last, when the failed site recovers or is repaired, mechanisms have to be available to integrate it smoothly back into the system. The recovery from failure in distributed systems is much more difficult than in a centralised system.