Chapter 4 Using the System Generator (SYSGEN)

SYSGEN is a utility used to modify the system configuration. System configuration changes are kept to disk in a configuration group or to a tape called a system load tape (SLT). The SYSGEN utility requires system supervisor (OP) capability to view system configuration and system manager (SM) capability to save changes or create an SLT.

SYSGEN contains a global module and four configurators:

Each configurator provides an interface to make changes to an independent portion of the configuration data and offers a menu of commands and online syntax help. Command names and abbreviations are easily identified. For example, the command to add a device is ADEV (abbreviated AD), while the command to delete a device is DDEV (abbreviated DD).

The configurators operate on information contained in the base configuration group. This basegroup is the group used to begin making changes to the system configuration. The basegroup includes a permanent set of configuration files that contain information on device classes, assigned I/O paths, assigned logical device (LDEV) numbers, current volume names, and various other system parameters.

Activating SYSGEN creates a set of temporary configuration files that correspond to the permanent file set specified with the BASEGROUP command. Configuration changes are made to the temporary configuration files. Once the changes are complete, the system manager uses the KEEP command to overwrite the permanent file set with the temporary file set or to save the temporary files to another permanent file set.

When KEEP is used to save changes to a new group name, SYSGEN stores the modified base group files in a group in the SYS account. The changes take effect once the system is rebooted with START NORECOVERY.

SYSGEN also provides a CLEAR command to erase changes made through one or more of the configurators.

	NOTE: When SYSGEN generates a boot tape, it writes the current configuration data as the group CONFIG.SYS, regardless of the group name on disk. CONFIG is the group selected by default by the START utility and used to start a system. For more information on the START utility, refer to Chapter 3 “System Startup Functions”