Resources controlled by Rational ClearCase are stored on a ClearCase server in repositories called versioned object bases, or VOBs. To access a VOB, you must connect to a ClearCase Web server and work in a ClearCase view. The ClearCase server may host one or more VOBs, or it may be part of a local area network to which other VOB hosts are connected.
VOBs store file system objects and metadata.
File system objects are files and directories. These objects are stored as elements, each of which contains one or more versions. A file element contains one or more versions of a file. A directory element contains one or more versions of a directory, each of which can contain file elements and other directory elements.
A version is a specific revision of a file or directory. Versions of text files are distinguished by changes in their text. Versions of directories are distinguished by changes in their contents (to account for files and subdirectories that have been renamed, removed, or added).
VOBs also store metadata such as comments, branches, labels, baselines and hyperlinks, which are associated with file system objects and their versions. The ClearCase Remote Client provides the ClearCase Navigator viewand ClearCase properties view with which you can view and, in some cases, modify VOB metadata.
When UCM is in use, the ClearCase Remote Client has access to special VOBs called Project VOBs. These VOBs typically contain only the metadata that project managers use to define UCM projects. When a project VOB contains definitions of many projects, related projects are often grouped into folders. When you join a UCM project, the Join UCM Project wizard displays a list of Project VOBs so that you can select the appropriate Project VOB and project.