Method and system for providing additional addressable functional space on a disk for use with a virtual data storage subsystem

A method for providing additional addressable space on a disk for use by a host processor using a virtual data storage subsystem comprising the steps of:

• a) defining at least one of a plurality of extended image devices as a multiple of a primary functional device for the purpose of copying tracks, wherein an addressable space on the at least one of the plurality of extended image devices is defined as an extension of an addressable space on the primary functional device, wherein the at least one of the plurality of extended image devices is identified by an Image Sequence Number, wherein the address of the instant image is passed to the data storage subsystem by passing a corresponding track address on the primary functional device, and by passing the Image Sequence Number through a new parameter setting in a Define Extent Channel Command Word of the data storage subsystem, such that the instant image is located on the at least one of the plurality of extended image devices identified by the Image Sequence Number;
• b) requesting an instant image utilizing channel command words of the data storage subsystem which reference the at least one of the plurality of extended image devices as a target for the instant image;
• c) reading an instant image utilizing channel command words of the data storage subsystem which reference the at least one of the plurality of extended image devices on which the instant image resides.

A method for providing additional addressable space on a disk for the copying of pointers to tracks by a host processor using a virtual Direct Access Storage Device subsystem comprising the steps of:

• a) defining at least one of a plurality of extended image devices as a multiple of a primary functional device, wherein an addressable space on the at least one of the plurality of extended image devices is defined as an extension of an addressable space on the primary functional device, wherein the extended image device is identified by an Image Sequence Number, wherein the address of the instant image is passed to the data storage subsystem by passing a corresponding track address on the primary functional device, and by passing the Image Sequence Number through a new parameter setting in a Define Extent Channel Command Word of the data storage subsystem, such that the instant image is located on the extended image device identified by the Image Sequence Number;
• b) requesting an instant image utilizing a command sequence where an address is passed through the Define Extent Channel Command Word, the address identifying a track on one of the plurality of extended image devices;
• and
• c) reading the instant image utilizing a ReadData Channel Command Word and the Define Extent Channel Command Word, the address of the instant image is passed through the Define Extent Channel Command Word, whereby the address allows the ReadData Channel Command Word to read the instant image which resides on a track outside of the primary functional device and within the extended image device.

A computer readable medium with computer instructions for providing addressable space on a disk for use by a host processor using a virtual data storage subsystem, the computer instructions for:

• a) defining an extended image device on a disk, wherein an addressable space on the extended image device is defined as an extension of an addressable space on a primary functional device, wherein the extended image device is identified by an Image Sequence Number, wherein the address of the instant image is passed to the data storage subsystem by passing a corresponding track address on the primary functional device, and by passing the Image Sequence Number through a new parameter setting in a Define Extent Channel Command Word of the data storage subsystem, such that the instant image is located on the extended image device identified by the Image Sequence Number;
• b) requesting an instant image to be addressed to an extended image device utilizing channel command words by a host process;
• and
• c) reading the instant image utilizing channel command words by the host processor.