StorageTek 6 Virtual Machine Configuration, Task Recovery/Termination, Tape Management System TMS

Task Recovery/Termination

Task recovery is concerned with resource recovery, possible retry operations, and the logging of software-detected errors. Terminations can be considered a special case of recovery where resources must still be recovered but no retry or logging is necessary. The SCP supports the most common ESTAE and ESTAI options and major SDWA fields. Recovery includes a disabled and enabled (scheduled task) mode. The resources being recovered are files to be closed, storage to be released, tasks to be terminated, and messages and scheduled interrupts to be cancelled.

Host Software Component (HSC)

The HSC runs as an application program in the SCP environment. The HSC source code is compiled by StorageTek.

The HSC accepts requests from the tape management interface (TMI) (see “Tape Management System (TMS)” below) and drives the library hardware.

Tape Management System (TMS)

The TMS uses the IUCV interface to communicate with the virtual machine. It provides a front end between the HSC and the user, and provides allocation, mount, and scratch pool services. The HSC provides the TMS with mount/dismount service and assists it in allocation for those volumes and drives which are under library control.

Note: In this document ‘‘TMS’’ is used to refer to any tape management system and not any particular product.

Operators and Utility Users

Operators use CP SMSG to communicate with the SCP via the CP Message System Service (*MSG). Utility users communicate with the SCP via punch spool files containing special control statements. The authorization services allows only specified users to access either of these interfaces; unauthorized users are disconnected from the service machine when any attempt is made to communicate with the subsystem.

Virtual Machine Configuration

Within a VM host system the following virtual machines (users) exist:

•operator(s)

•ACS service machine (SCP and HSC)

•TMS service machine

•administrator(s)

•TMS requestors.

Various illustrations are provided to show relationships. Figure 2 on page 11 illustrates the relationship of users to each other and the virtual machine and hardware relationships.

Figure 3 on page 12 illustrates how the library data sets may be shared by multiple, dissimilar host systems.

Chapter 1. System Description 9

1st ed., 6/30/04 - 312579601