James Allen Zahrobsky

US Patent:

52476189, Sep 21, 1993

Filed:

May 11, 1992

Appl. No.:

7/882765

Inventors:

Scott H. Davis - Merrimack NH
William L. Goleman - Nashua NH
David W. Thiel - Amherst NH
Robert G. Bean - Colorado Springs CO
James A. Zahrobsky - Colorado Springs CO

Assignee:

Digital Equipment Corporation - Maynard MA

International Classification:

G06F 1314

US Classification:

395275

Abstract:

A method and apparatus for transferring data between two storage media, and is used in an illustrative embodiment to transfer data between two storage media in a shadow set, the storage media being accessible to one or more host processors. The method of the preferred embodiment includes the steps of: A. receiving a command from one of the host processors, the command specifying data to be transferred from a first storage medium to a second storage medium; B. transferring the data specified in the command received from the host from the first storage medium to the second storage medium in a series of subtransfers, each of the subtransfers transferring a portion of the data; and C. processing one or more I/O requests to the shadow set received from one or more host processors by, for each received I/O request: a. implementing the I/O request if the I/O request does not involve a section of the shadow set currently involved in one of the subtransfers; and b. stalling the I/O request if the I/O request involves a section of said shadow set currently involved in one of the subtransfers, and implementing the I/O request when the subtransfer has completed.

US Patent:

55465366, Aug 13, 1996

Filed:

Mar 23, 1995

Appl. No.:

8/409905

Inventors:

Scott H. Davis - Merrimack NH
William L. Goleman - Nashua NH
David W. Thiel - Amherst NH
Robert G. Bean - Colorado Springs CO
James A. Zahrobsky - Colorado Springs CO

Assignee:

Digital Equipment Corporation - Maynard MA

International Classification:

G06F 1108
G06F 1114

US Classification:

39518218

Abstract:

A log for managing data in a shadow set of storage media includes a system for maintaining a log of address information associated with at least one write command received from one of a plurality of data processing devices. The system for maintaining a log of address information includes a device for receiving a write command from a data processing device, a device which writes data associated with the write command in a section of one of the storage media, and a device which writes address information in a log indicative of the location of that section. A device is provided which then implements a management operation on data stored on one of the storage media in accordance with the address information stored in the log.