What Are Local and Global Resources?

A local resource is known only to the system on which it resides. Only authorized users on the local system can access local resources. The name of a local resource must be unique only within the local system. Resources (for example, a printer) that should be limited to the users of one system should be defined as a local resource to that system.

For a local resource, the VM system on which the resource resides can be thought of as the LU for an allocation request. The LU name is *IDENT.

A global resource is known to all systems in the TSAF or CS collection. Authorized users in the TSAF or CS collection or the SNA network can access global resources. Each global resource name must be unique within the TSAF or CS collection in which it resides. Resources (for example, databases) that contain dynamic information needed by users in the TSAF or CS collection should be defined as global.

Global and local server virtual machines are explicitly logged on and the resource managers are explicitly called. Therefore, the resource managers are always ready for requests.

If a local and global resource are defined with the same name, the resources are accessed as follows:

When a user on the local z/VM system requests to communicate with the resource, CP routes the user to the local resource. If the resource is unavailable or is not known on the local system, TSAF or ISFC routes the request to the global resource.
When a remote user on another z/VM system in the TSAF or CS collection requests to communicate with the resource, TSAF or ISFC routes the user to the global resource, even if a local resource with the same name also exists on the target system.

For example, a TSAF collection contains two printers. Printer A is a local resource on System A; Printer B is a global resource on another system in the TSAF collection. Each printer is identified by the resource name PRINTER. When a user on System A requests to communicate with the resource PRINTER, the request is routed to the local printer, Printer A. However, if Printer A is not available, the local user will be routed to the global resource PRINTER, Printer B.

For global resources, the TSAF and CS collection in which the resource resides can be thought of as the LU. In this case, the LU name is *IDENT.