Modification management in multiple replicas: Mastership

Because changes are made independently at multiple replicas, these changes may conflict. In a MultiSite environment, tracking changes and preventing data corruption are accomplished with an exclusive-right-to-modify scheme called Mastership. Mastership determines when a user of a replica is allowed to modify data.

If the work done in different replicas were truly independent, the result would be chaos. If a record SAMPL00001 is created in three replicas at the same time, it is impossible to determine which is the real record SAMPL00001 and what must happen to the other two records.

Certain objects are assigned a master replica (or master). The initial master of an object is the replica where the object is created, and mastership can be changed subsequently . In general, an object can be modified or deleted only at its master replica.

Most objects in a Rational® ClearQuest® database have a master replica.

Some conflicts are unavoidable. For example, a new user named jsmith can be created at two or more sites during the same time period between synchronizations. You can minimize such conflicts by establishing naming conventions for objects, but if a conflict does occur, it is handled during import of an update packet.