StorageTek Host Software Component 6 User Manual

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4   VM/HSC 6.0 System Programmer’s Guide
1st ed., 6/30/04 - 312579601
HSC Subsystem Components 
The HSC is a secondary subsystem that executes in various environments including a 
standard class G virtual machine. The HSC contains the following components: 
• External Components — External components interface with other virtual 
machines, an operator, an administrator, and/or a system programmer. The external 
components consist of an installation component, the initialization/termination 
component, a command component, the utility component, and a tape management 
interface component. 
• Common Components — Common components provide distinct functions required 
by the external and common components. The common components consist of the 
mount/dismount components, the CAP component, and the recovery component. 
• Control Components — Control components provide logical control over system 
entities used by both common components and external components. The control 
components consist of the volume/cell control component and the configuration 
control component. 
• Server Components — The server components provide physical control of system 
entities for the control components. The server components consist of the data base 
server, the LMU server, the WTO component, and the address space communications 
server. 
HSC Architecture 
Note: In this discussion, address space refers to a virtual machine. 
Figure 1 on page 5 displays external components located in the user’s address space on the 
left side, and other HSC components located in the HSC’s address space on the right side. 
Note: The initialization/termination external component resides entirely in the HSC 
address space. 
The Address Space Communications Server spans the user’s address space and the HSC 
address space. It handles requests from components in the user’s address space that require 
services from components located in the HSC’s address space. 
The following section briefly describes the functions of each external component.
Operator Command component
The operator command component receives control from other virtual machines to 
process an HSC command or to call upon services in the HSC. 
Batch Utilities external component 
The utility component exists mostly within the service machine. However, a few 
utilities execute in the invoker’s CMS virtual machine.