Emc Corporation

Daniel A Murphy

Douglas Eric LeCrone

Yuval Ofek

Denis Hall

William R Fairchild

Natan Vishlitzky

Paul A Linstead

Hana Moreshet

Michael E Specht

Eugene D Pflueger

Martin Farley

Kevin C Heasley

Izhar Sharon

Elizabeth E Patapoutian

Raymond Wong

Stewart C Woodworth, Iii

A method and apparatus for monitoring update activity, particularly in the form of write requests, to a data storage facility, over at least one cycle to identify any write operation or update that occurs to that data storage facility on a track-by-track basis. At the end of each cycle a list of changed tracks is stored in a data set. After information has been accumulated by a collector application, a reporter application manipulates the data to obtain information concerning the track changes and to estimate communication path requirements.

Program for monitoring update activity in a data storage facility

A data-mirroring method in which, while an I/O process is processing a first I/O request for writing data to a first device, control is obtained from that I/O process executing on a host computer. A second I/O request, this one for writing the data to the second device, is then created. Then, control is returned to the I/O process by causing the first I/O request to be made available to a first data storage system managing the first device.

Intercepting control of a host I/O process

A method and apparatus for assuring data consistency in a data processing network including local and remote data storage controllers interconnected by independent communication paths. The remote storage controller or controllers normally act as a mirror for the local storage controller or controllers. If, for any reason, transfers over one of the independent communication paths is interrupted, transfers over all the independent communication paths to predefined devices in a group are suspended thereby assuring the consistency of the data at the remote storage controller or controllers. When the cause of the interruption has been corrected, the local storage controllers are able to transfer data modified since the suspension occurred to their corresponding remote storage controllers thereby to reestablish synchronism and consistency for the entire dataset.

Method and apparatus for maintaining data coherency

A method for enabling overlapped input/output requests to a logical device using assigned and parallel access unit control blocks. Each I/O request interrupts an operating system to assign a base and related unit control block to the input/output requests. In addition a parallel access control block is associated with each unit control block for a logical volume and a parallel access main control block is established with a logical volume through which each of the base and related unit control block can be identified. An input/output request to a logical device interrupts the operating system to assign one of the base and one of the assigned unit control blocks to the input/output requests after which control transfers back to the operating system. At a disk storage facility, the input/output request is located in a table with other input/output requests and corresponding parameters. The disk array storage facility tests the parameters for each new input/output request to determine which of a plurality of control functions will be performed.

Method for enabling overlapped input/output requests to a logical device using assigned and parallel access unit control blocks

Method and apparatus for monitoring update activity in a data storage facility

A method for enabling a data processing system with a host running under an operating system and with a disk array storage device organized by logical devices to process panel I/O requests to a logical device from one or more host processors concurrently. The system includes a parallel access control block that identifies unit control blocks assigned to the same logical device. If an I/O request is received while a main UCB unit is busy, the main control block identifies another unit control block to enable an overlapped access to the logical device.

Operating system for generating overlapped input-output requests to a device in a disk array storage

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Hopkinton, MA, United States of America

Daniel A Murphy