Replicated VOB databases

In DevOps Code ClearCase® MultiSite, developers at different geographic locations can use the same versioned object base (VOB), because each site has its own copy (replica) of the VOB.

A VOB provides permanent storage for an entire directory tree: directories, files, and links. The historical versions of the files in the VOB are stored in data container files in storage pool directories. The VOB database records the evolution of the version-controlled file system objects and stores the associated metadata, including version labels, hyperlinks, configuration records, and so on. For more information about VOB data structures, see the DevOps Code ClearCase documentation.

If DevOps Code ClearCase MultiSite is not used, each VOB has a single set of data containers and a single database. With MultiSite, some or all VOBs are replicated. A replicated VOB is located at multiple sites; at each site is a copy of the VOB, called a VOB replica. Collectively, the set of replicas of a VOB is called a VOB family. Each replica includes a full set of data containers and a complete copy of the VOB database. At its site, a replica appears to be a regular VOB; developers can check out, edit, and check in; build software; attach metadata annotations to objects; and so on. Regular DevOps Code ClearCase use models apply to use of replicas, but there are some coordination issues that administrators must consider. (For more information, see Implementation planning.) Also, MultiSite features allow simultaneous development to occur at different replicas without conflicts. Independent development: Mastership describes how conflict avoidance works.

For more information, see VOBs and VOB replicas, VOB objects and VOB replica objects and DevOps Code ClearCase commands related to DevOps Code ClearCase MultiSite.