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Generating Logical Unit Addresses Based Upon Interruption Signals

IP.com Disclosure Number: IPCOM000085423D
Original Publication Date: 1976-Apr-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Angstadt, RA: AUTHOR [+3]

Abstract

In a virtually addressed mass storage system (MSS) having several stages of address translation, error recovery from a disk storage unit or spindle can be achieved by moving a disk pack from one spindle to another. This can be done within one staging drive group (a set of spindles attached to a given disk controller) or between staging drive groups. In either event, the disk storage units subjected to pack swapping are varied off, i.e., logically no longer belong to MSS.

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Generating Logical Unit Addresses Based Upon Interruption Signals

In a virtually addressed mass storage system (MSS) having several stages of address translation, error recovery from a disk storage unit or spindle can be achieved by moving a disk pack from one spindle to another. This can be done within one staging drive group (a set of spindles attached to a given disk controller) or between staging drive groups. In either event, the disk storage units subjected to pack swapping are varied off, i.e., logically no longer belong to MSS.

Upon completion of the pack swap, each of the swapped packs actuates a corresponding receiving disk storage unit to generate a pack change interrupt (PCI). PCI flows through the disk controller to a director staging adapter (DIRSA). Since DIRSA has no logical unit address (LUA) or any table entries for the received PCI, it sends a message to this effect to mass storage control (MSC).

A microprogram in MSC, called the interrupt saver, at step 1, then goes to a SSID (physical map of MSS) page availability table for the given staging drive group from which the PCI was received. Associated with the PCI will be a real unit address (RUA) indicating the physical address of the spindle.

If the RUA is address G in a given staging drive group, a logical unit address (LUA) is generated based upon the address offset from the lowest address of the page availability table for the given staging drive group. This address offset computed LUA is sup...