International Business Machines Corporation

James Elkins McIlvain

William C Shepard

Harry M Yudenfriend

Brent Cameron Beardsley

Robert Wesley Shomler

James Lincoln Iskiyan

Michael Aloysius Paulsen

Philip Ray Mills

William G Thompson

Disclosed is a system for performing input/output (I/O) operations with a processing unit. A processing unit, such as a host system, determines a base and associated alias addresses to address an I/O device, such as a direct access storage device (DASD). The processing unit associates the determined base and alias addresses to the I/O device. The association of base and alias addresses is maintained constant for subsequent I/O operations until the processing unit detects a reassignment of the association of base and alias addresses. The processing unit then determines an available base or alias address to use with an I/O operation and may concurrently execute multiple I/O operations against the I/O device using the base and alias addresses.

System for accessing an input/output device using multiple addresses

A logical positioning mechanism is provided within a storage controller, thus enabling the storage controller to determine which logical position in a storage device is to be accessed next. The logical positioning mechanism includes one or more logical position indicators defined, maintained and controlled by the storage controller. The logical position indicators include the address of the logical position to be next accessed and are incremented and decremented by the storage controller depending upon the operation accessing the logical position.

Logical positioning within a storage device by a storage controller

A method and system for asynchronous remote data duplexing at a distant location from copies based at a primary site storage subsystem, which copying is non-disruptive to executing applications, and further in which any data loss occasioned by losses in flight or updates never received at the time of any interruption between the primary and remote sites are accounted for at the remote site. The method assigns a token and unique sequence number responsive to each write operation at the primary site, and sends the tokens+numbers and data updates to the remote site. The method relies upon the sequence number to establish a sequency and define gaps therein to ascertain missing updates.

Method and arrangement for multi-system remote data duplexing and

Growing community of inventors

Los Gatos, CA, United States of America

James Elkins McIlvain