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Patent Title: Intelligent controller accessed through addressable virtual space

Assignee: Computer Associates International, Inc.
Patent Number: US6493811
Issue Date: 12-10-2002
Application Number:
File Date:01-20-1999

Abstract: File operations on files in a peripheral system are controlled by an intelligent controller with a file processor. The files are accessed as if the intelligent controller were an addressable virtual storage space. This is accomplished first by communicating controller commands for the intelligent controller through read/write commands addressed to a Command Region of a virtual storage device. The controller commands set up a Mapped Data Region in the virtual storage device for use in controlling data transfer operations to and from the peripheral system. With the Mapped Data Regions set up, blocks of data are transferred between the host and the intelligent controller in response to read/write commands addressed to the Mapped Data Region of the virtual storage device. In an additional feature of the invention file operations are communicated between host and controller through a device driver at the host and a device emulator at the intelligent controller. If the address in the device write/read command is pointing to the Command Region of the virtual storage device, a Command Region process interprets and implements the controller operation required by the controller command embedded in the device write/read command. One of these controller commands causes the Command Region processor to map a requested file to a Mapped Data Region in the virtual storage device. If the address detected by the detecting operation is in a Mapped Data Region, a Mapped Data Region process is called. The Mapped Data Region process reads or writes requested data of a file mapped to the Mapped Data Region addressed by the read/write command. This mapped file read or write is accomplished as a transfer of data over a data path separate from a control path. In an additional feature of the invention, the data transfer between host system and intelligent controller is accomplished by performing a direct memory access transfer of data.


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