Deleted data file space release system for a dynamically mapped virtual data storage subsystem

Patent 5193184 Issued on March 9, 1993. Estimated Expiration Date:

June 18, 2010. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

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Inventors

Assignee

Storage Technology Corporation

Application

No. 540500 filed on 06/18/1990

US Classes:

711/4, Dynamic-type storage device (e.g., disk, tape, drum)707/200, FILE OR DATABASE MAINTENANCE711/114, Arrayed (e.g., RAIDs)711/207Directory tables (e.g., DLAT, TLB)

Examiners

Primary: MacDonald, Allen R.
Assistant: Sheikh, Ayaz R.

Attorney, Agent or Firm

Duft, Graziano & Forest

International Class

G06F 011/00

Abstract

The deleted dataset space release system provides facilities in a dynamically mapped virtual memory data storage subsystem to immediately release the physical space occupied by a deleted dataset for use by the data storage subsystem to store subsequently received data files. This system also provides data security by preventing the unauthorized access to the data of scratched data files, both in cache memory and on the data storage devices. The deleted dataset space release system utilizes a user exit in the host processor data file scratch routine to transmit information to the data storage subsystem indicative of the host processor data file scratch activity. Existing channel command words are used in a manner that is transparent to the host processor. The data storage subsystem thereby immediately receives an indication that the host processor is scratching a data file from the volume table of contents of a virtual volume. The data storage subsystem can then concurrently scratch this data file from the virtual track directory contained in the data storage subsystem and thereby release the physical storage space occupied by this scratched data file.