VOBs and VOB Replicas


Each replica has a replica name in addition to a VOB tag. You specify both the replica name and the VOB tag when you create the replica. For each replica, the VOB database contains a replica object that records the name of the replica. The VOB database also tracks the location of each replica by host name. This tracking enables MultiSite administrators to specify replicas at other sites with short, mnemonic identifiers, without needing to know their exact locations.

Each replica is a copy of the VOB, including both file system data (data containers) and metadata (VOB database). At each replica, developers can see all VOB elements and all versions of each element.

The replicas are not necessarily exact copies of each other. MultiSite features accommodate typical differences among sites:

Most, but not all, of the information stored in a VOB is replicated. All changes that create new data, remove old data, and move or rename existing data are propagated among the replicas in the VOB family. However, information stored in views is not propagated. For example, a replica update includes the fact that an element has been checked out, because the checkout is recorded in the VOB; but the update does not include the contents of the checked-out version.

For more information, see Information Propagated Among VOB Replicas.

The biggest difference among replicas reflects the basic capability of MultiSite: enabling development work to proceed independently at different locations. For more information, see Enabling Independent Development: Mastership.