3.5 Planning PVOBs

ClearCase stores UCM objects such as projects, streams, activities, and change sets in project VOBs (PVOBs). PVOBs can also function as administrative VOBs. You need to decide how many PVOBs to use for your system and whether to take advantage of the administrative capabilities of the PVOB.

Deciding How Many PVOBs to Use

PRODUCT NOTE: This section does not apply to Rational ClearCase LT because that product allows for only one PVOB per server.

Projects that use the same PVOB have access to the same set of components. If developers on different projects need to work on some of the same components, use one PVOB for those projects. For example, Figure 14 shows concurrent development of two versions of the Webotrans product. While most members of the team work on the 4.0 release in one project, a small group works on the 4.0.1 release in a separate project. Both projects use the same components, so they use one PVOB.

Figure 14 Related Projects Sharing One PVOB

Consider using multiple PVOBs only when one or both of the following conditions applies:

• The projects do not share components, and you anticipate that they will never need to share components.

• The projects are so large that PVOB capacity becomes an issue.

Understanding the Role of the Administrative VOB

An administrative VOB stores global type definitions. VOBs that are joined to the administrative VOB with AdminVOB hyperlinks share the same type definitions without having to define them in each VOB. For example, you can define element types, attribute types, hyperlink types, and so on in an administrative VOB. Any VOB linked to that administrative VOB can then use those type definitions to make elements, attributes, and hyperlinks.

If you currently use an administrative VOB, you can associate it with your PVOB when you create the PVOB. ClearCase then creates an AdminVOB hyperlink between the PVOB and the administrative VOB. Thereafter, when you create components, ClearCase creates AdminVOB hyperlinks between the components and the administrative VOB so that the components can use the administrative VOB's global type definitions.

If you do not currently use an administrative VOB, do not create one. When you create components, ClearCase makes AdminVOB hyperlinks between the components and the PVOB, and the PVOB assumes the role of administrative VOB.

For details on administrative VOBs and global types, see the Administrator's Guide for Rational ClearCase or the Administrator's Guide for Rational ClearCase LT.