Registry regions

Each Rational® ClearCase® client is a member of a single registry region and can access only those VOBs and views whose tags are registered in that region.

A registry region is a tag namespace. With the Rational ClearCase registry, you can create multiple regions. VOB and view tags in a Rational ClearCase registry include the name of the registry region in which the tag is visible.

The registry initially has one region, as shown in Figure 1. All clients are members of this region. All tags are created in this region, and are visible to all clients of the registry host.

Figure 1. Registry with one region

Figure 1. shows a registry with one region. A VOB tag and a view tag in the default region point to their corresponding VOB_object and view_object entries in the registry.

The most common reason for creating an additional region is to accommodate the different network file system naming conventions of each supported operating system when Windows® hosts that use dynamic views need to access VOBs or views hosted on Linux® or on the UNIX® system. (Snapshot and Web views do not require network file system access to VOB server hosts.)

Figure 2 illustrates a registry with two regions: one for Windows clients, in which global paths are expressed as UNC names, and another for clients running Linux or the UNIX system, in which global paths are expressed as NFS pathnames.

Note: Establish uniform naming standards when creating tags in multiple regions. For example, preserving the leaf name sources in the Linux or UNIX system-based tag /vobs/sources and the Windows tag \sources, makes it easier for users to know that the two tags refer to the same VOB.

Figure 2. Registry with two regions

Figure 2. shows a registry with two regions, one on Windows and one on the UNIX system.

Regardless of how many regions a registry has, each VOB or view tag in a region references a single underlying VOB or view object entry, which must exist before any tag can be created.

You might need to create additional regions for any of the following reasons:

Your network includes VOB or view server hosts that have multiple network interfaces and, therefore, multiple host names.
You create VOB or view tags that include multibyte characters, and the registry serves clients that do not use the same setting for operating system locale. Because the interpretation of multibyte characters is controlled by a host's locale setting (established on Linux and on the UNIX system through the LOCALE environment variable, and on Windows by using the Regional Options tool in Control Panel), all tags in a region must use the same character set, and all hosts in a region must use the same locale setting.
You want to prevent access to specific VOBs or views from specific clients by assigning those clients to a region where tags for those VOBs or views do not exist.

A Rational ClearCase host is typically assigned to a region during the installation. You can change this assignment later if necessary by following the procedures in Assigning a host to a new registry region. To display a host's region, use the host node of the Rational ClearCase Administration Console, the ClearCase program in Control Panel, or the cleartool hostinfo –long command.

Note: A VOB must have a tag in the region to which its server host is assigned. A VOB can have tags in other regions also.