Overview of the User Directory
The z/VM user directory specifies the configuration and operating characteristics of virtual machines. A z/VM user directory exists in two forms: a source form that consists of one or more CMS files, and an object form, created from the source, on a CP-formatted disk. Multiple object directories can be accessed by the z/VM system, but only one object directory can be active (online) for a system at any given instant.
Important: When operating in an SSI cluster environment, you should use a single source directory to create the object directory for each member in the SSI cluster. Using a single source directory results in consistent set of virtual machine configurations on each system in the SSI cluster.
The source form of the user directory consists of directory statements that define the CP-formatted volume on which the object directory is created and the configuration and operating characteristics of the virtual machines that are known to the z/VM operating system. The directory statements are divided into blocks called entries. An entry begins with one of the following statements: GLOBALDEFS (global definitions entry), PROFILE (profile entry), USER (user entry), IDENTITY (identity entry), or SUBCONFIG (subconfiguration entry).
- Single-configuration virtual machine definition
- A virtual machine definition that
consists of a user entry and any included profile entry. Only one virtual machine instance can be
created from a single-configuration virtual machine definition. For example, you can specify a USER1
single-configuration virtual machine and log on to a z/VM system as USER1.
In an SSI cluster, the virtual machine can be logged on to only one SSI member at a time.
- Multiconfiguration virtual machine definition
- A virtual machine definition that consists of an identity entry, any included profile entry, and all associated subconfiguration entries. In an SSI-enabled source directory, this virtual machine definition allows multiple virtual machine instances to be defined, which enables the user ID to be logged on concurrently to multiple members of the SSI cluster. Each of these virtual machine instances can have a different configuration from the others. For example, you can define a MAINT multiconfiguration virtual machine and concurrently log on to all the members of an SSI cluster as MAINT.
Figure 1 is an abbreviated view of two virtual machine definitions, one a single-configuration virtual machine and the other a multiconfiguration virtual machine. The sample source directory defines USER1 as a single-configuration virtual machine through the USER and associated directory statements, allowing USER1 to log onto one member of the SSI cluster at a time. In this case, USER1 has logged onto SYS4. The sample source directory defines MAINT as a multiconfiguration virtual machine through the IDENTITY, BUILD, SUBCONFIG, and associated directory statements, allowing MAINT to log onto all members of the SSI cluster concurrently, using common settings from the identity entry and system-unique settings from the subconfiguration entry.
