International Business Machines Corporation

Hitachi Data Systems Corporation

Claus William Mikkelsen

William Frank Micka

Robert Frederic Kern

Robert Wesley Shomler

Michael Howard Hartung

James Mitchell Ratliff

Oded Cohn

Kenneth M Nagin

Lawrence E Eastridge

Yoram Novick

Ronald Maynard Kern

Alexander Winokur

John N McCauley, Jr

Richard Allan Ruehle

Cynthia Anne Martinage

Michael John Dutch

William David Davenport

Gregory E McBride

David Michael Shackelford

Warren Keith Stanley

John Norbert McCauley

Richard K Treiber

Michael Aloysius Paulsen

May Ngun Wone

In a computer system, the controller of one or more primary data recording devices sends update information to the controller of one or more secondary data recording devices to maintain a remote copy of data stored on the primary data recording devices. The primary controller receives a command from a computer that specifies a prospective suspend time after which remote copy operation is to be suspended. After the suspend time passes, the primary controller stops sending the update information to the secondary controller and begins storing indicators of the updated information in cache memory. The primary controller may resume remote copy operation in response to a command received from the computer by first entering into a pending mode of operation in which cached indicators are used to identify update information that must be sent to the secondary controller to resynchronize the remote copy. When the information for all cached indicators has been sent, normal remote copy operation may be resumed.

Remote data copy using a prospective suspend command

A method and system are disclosed for enhanced efficiency of backup copying of designated datasets stored within a plurality of storage devices coupled to the data processing system via a storage subsystem control unit having subsystem memory therein. Application execution within the data processing system is temporarily suspended long enough to form a dataset logical-to-physical system address concordance to be utilized to administer copying of the designated dataset. Thereafter, application initiated updates to uncopied portions of the designated datasets are temporarily deferred until sidefiles of the affected portions of the designated datasets are written to subsystem memory. The updates are then written to the storage subsystem. Portions of the designated datasets are then accessed and copied from the storage subsystem on a scheduled or opportunistic basis utilizing selected data retrieval command sequences. A sidefile status query is appended to selected data retrieval command sequences and the presence of data within the subsystem memory is determined without the necessity of additional communications between the data processing system and the storage subsystem. The sidefiles are then accessed and copied. Copied portions of the designated datasets and sidefiles are then copied to alternate storage locations in a backup copy order defined by the address concordance.

Method and system for sidefile status polling in a time zero backup copy process

A method in a data processing system for automatically terminating or resuming backup copy sessions after an abnormal interrupt or reset notification occurrence during a backup copy process. A status indication is entered into activity tables associated with a plurality of storage subsystems and devices within a data processing system in response to initiation of a backup copy session. Status indications are then entered upon successful completion of a backup copy session within the data processing system. The indications within the activity tables are reviewed to determine the status of a backup copy session upon restarting a resource manager, abnormal termination of a backup copy program, or an operating system initial program load. If a backup copy session has been initiated but not completed, the backup copy session is then terminated. The indications within the activity tables are also reviewed to determine the status of a backup copy session if a reset notification is raised by a storage subsystem. The tracks extents which are active for a volume associated with a particular session identification are determined. A comparison is then made between the tracks extents which are active and the volume and extent information associated with a physical session identification. If a match exists between the tracks extents which are active and the volume and extent information associated with a physical session identification, the backup copy session resumes. If a match does not exist, the backup copy session is terminated.

Method and system for automated termination and resumption in a time zero backup copy process

A remote data shadowing system provides storage based, real time disaster recovery capability. Record updates at a primary site cause write I/O operations in a storage subsystem therein. The write I/O operations are time stamped and the time, sequence, and physical locations of the record updates are collected in a primary data mover. The primary data mover groups sets of the record updates and associated control information based upon a predetermined time interval, the primary data mover appending a prefix header to the record(updates thereby forming self describing record sets. The self describing record sets are transmitted to a remote secondary site wherein consistency groups are formed such that the record updates are ordered so that the record updates can be shadowed in an order consistent with the order the record updates cause write I/O operations at the primary site.

Forming consistency groups using self-describing record sets for remote

A disaster recovery system providing asynchronous remote data shadowing between a primary and a secondary site uses a pair of track arrays for each primary data storage device of a remote copy pair to monitor which record updates are in transit between the primary site and the secondary site. A host processor at the primary site of the disaster recovery system transfers a sequentially consistent order of copies of record updates to the secondary site for back-up purposes. The copied record updates are stored on the secondary data storage devices which form remote copy pairs with the primary data storage devices at the primary site. One track array, the active track array, is used to set elements according to which tracks on the primary data storage device receive record updates from the host processor at the primary site. The other track array, the recovery track array, designates which record updates comprise the copied record updates currently transferred from the primary site to the secondary site for data shadowing and is used for recovery should an error interrupt the transfer. The track arrays are toggled once the consistency group transfer completes, the recovery track array becoming the active track array and the active track array becoming the recovery track array.

Asynchronously shadowing record updates in a remote copy session using

A remote data shadowing system provides synchronous, storage based, real time disaster recovery wherein a secondary site is located remote from the primary site. An error recovery program at the primary site quiesces applications running thereat for performing error recovery procedures and signalling both primary and secondary locations that failed duplex has occurred. The error recovery program determines the cause of failed duplex, and if error recovery is successful, duplex mode is resumed. If the error recovery program is unable to perform error recovery successfully, then further write updates at the primary site are prohibited and an error message is communicated to operators at both the primary and secondary sites.

Remote data duplexing

A data copy validation technique compares primary data to a copy of that data by generating check codes of the data to be validated at both primary and secondary sites in a continuously running remote data shadowing system. The validation session runs concurrently with the data shadowing so as not to disrupt the data shadowing. Each data validation session is assigned a copy start time, for example, a time preceding a time of a consistency group, for defining when the check code for data at the primary should be compared to a check code of the data at the secondary. The check code of the data at the secondary site is taken at a time that is the equivalent logical point-in-time of that data at the primary site even though the respective data contents may be different in real time.

Remote copy secondary data copy validation-audit function

A system for asynchronously duplexing direct access storage device (DASD) data in a plurality of DASD subsystems has the advantage of decoupling the data duplexing operation from the DASD write I/O operation. This ensures the write does not incur unnecessary wait states in the subsystem. By establishing a sequence checkpoint at which time a set of information packets are grouped together and processed as a single sequence unit, this decoupling and independent operation takes place. Through this independence, data copying to a secondary location can take place without affecting the performance of the subsystems and also not affecting the corresponding integrity of the data that is being updated.

System for asynchronously duplexing remote data by sending DASD data

A method and system are disclosed for permitting high concurrency of access during backup copying of designated data stored within a storage subsystem which includes multiple storage devices coupled to the data processing system via a storage subsystem control unit having subsystem memory therein. Data within each storage device is accessed utilizing a Unique Control Block (UCB), which identifies a selected storage device, and an associated data retrieval command sequence which identifies the data to be accessed. Portions of the data copied to subsystem memory within the subsystem storage control unit as sidefiles from a first storage device may be accessed utilizing a Unique Control Block (UCB) associated with an alternate storage device by associating a selected data retrieval command sequence therewith which identifies the data as stored within the subsystem memory. In this manner, data from a first storage device may be accessed utilizing an alternate Unique Control Block (UCB), permitting concurrent access of data utilizing the Unique Control Block (UCB) associated with the first storage device.

Method and system for concurrent access during backup copying of data

A method in a data processing system for generating a backup copy of designated datasets during concurrent execution of an application. Upon receiving a request for a backup copy, execution of an application is suspended. A dataset logical-to-physical storage system address concordance for the designated datasets is formed, and execution of the application is resumed thereafter. A resource manager is established to manage all input and output functions between storage subsystems, storage subsystem memory associated with each of the storage subsystems, and a temporary host memory during formation of the backup copy. Formation of the backup copy is accomplished on a scheduled or opportunistic basis by copying the designated datasets from the storage subsystems and then updating the address concordance in response to the copying. Application updates are processed during formation of the backup copy by buffering the updates, copying the affected uncopied designated datasets to a storage subsystem memory, updating the address concordance in response to the copying, and processing the updates. Designated datasets can also be copied to the temporary host memory in the event the number of designated datasets in the storage subsystem memory exceeds a threshold number. Finally, the designated datasets are copied to an alternate storage memory from the storage subsystem, storage subsystem memory and temporary host memory utilizing the resource manager and the altered address concordance to create a specified order backup copy of the designated datasets from said copied portions of the designated datasets without user intervention.

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San Jose, CA, United States of America

Claus William Mikkelsen