International Business Machines Corporation

Dean Lee Hanson

Kenneth Fairclough Day, Iii

Douglas William Dewey

Mark Albert Reid

Keith Anthony Bello

Gregory Tad Kishi

Jonathan Wayne Peake

William David Lamear

Susan Kay Candelaria

Thomas W Bish

David Allan Pease

Donald M Nordahl

William G Sherman, Ii

Robert L Kwok

Kenneth Wayne Lane

Norman Iwao Hanami

A method to write information to two virtual tape servers. The method writes a file to a virtual host device disposed in a first virtual tape server, where the virtual host device comprises an adjustable bandwidth. The method queues a job to copy the file to a second virtual tape server, determines the age of the copy job, and copies that file to the second virtual tape server. The method sets an age threshold, and determines if the copy job age is greater than that age threshold. If the copy job age is greater than the age threshold, then the method decreases the adjustable bandwidth, if not, the method restores the adjustable bandwidth.

Apparatus and method to write information to two virtual tape servers

An increase in the efficiency of copy operations in a data storage system is provided. A host device directs that a volume of customer data be stored through one of two virtual storage servers on media in an associated library. An initiating controller queues a request to copy the volume to a second library. If the request is not processed by the initiating controller within a predetermined period, the initiating controller broadcasts the copy request to other controllers, each of which queues the request. After one of the controllers processes the request and the volume has been copied to the second library, the processing controller broadcasts a message to the other controllers which then dequeue the copy request from their respective copy queues. Upon receipt of such message, the initiating controller transmits a message to the host device that the volume was successfully stored and copied.

Self-optimizing workload distribution among virtual storage controllers

A method to write information to two geographically separated virtual tape servers, where the method provides a file to a virtual tape controller, writes that file to a first virtual tape server, and queues a copy job for the file in the virtual tape controller. Subsequently, the method provides the file to a second virtual tape server. The method sets a throughput threshold, determines the actual VTC throughput, and determines if the actual VTC throughput exceeds the throughput threshold. The method sets an age threshold and determines if the copy job age is greater than that age threshold. If the actual VTC throughput is greater than the throughput threshold and the copy job age is greater than the age threshold, then the method decreases the first adjustable host bandwidth and/or the second adjustable host bandwidth, otherwise the method restores the bandwidth to a nominal value.

Apparatus and method to write information to two geographically separated virtual tape servers

A disk caching method for an intermediary controller is disclosed. Requests for data blocks are made and then disk caching is performed according to a most expedient cache method. The disk caching method may be performed by asynchronously requesting a data record from both a intermediary controller disk storage and from a intermediary controller cache and using a first received copy of the data record, the first received copy being a copy received first from the intermediary controller disk storage. Alternatively, the disk caching may be performed by searching an intermediary controller cache to determine whether requested data is located in the cache of the intermediary controller, searching a storage device of the intermediary controller to determine whether requested data is located in the storage device of the intermediary controller and retrieving the requested data from a disk controller coupled to the intermediary controller when the requested data is not in the cache or storage device of the intermediary controller. The intermediary controller maintains a cache hit ratio for cache in a disk controller cache and chooses a cache method based upon a comparison of the hit ratio to the threshold. The intermediary controller selects an item to replace in the intermediary controller cache, moves data into the intermediary controller cache, determines whether the hit ratio of the disk controller is greater than the threshold and moves the item into the intermediary controller storage device when the hit ratio of the disk controller cache is greater than the threshold. The intermediary controller discards the item form the cache of the intermediary controller when the hit ratio of the disk controller is not greater than the threshold.

Method and apparatus for disk caching for an intermediary controller

A particularly efficient storage system makes redundant copies of data on tape by waiting until a rewind/unload command is received and then copying stored data objects en masse, thereby benefitting from any data compression used to store the objects along with the lower overhead for the copy operation. This copy operation is more efficient than the data objects' original storage, because there is less overhead in copying the data objects en masse; also, there is less data to copy if the data objects were stored with any data compression. Efficiency may be further increased by dividing the task of originally writing the data objects between paired tape drives, and then exchanging data objects between the tape drives upon issuance of the rewind/unload command.

Backup copy achieving improved efficiency by waiting until rewind/unload command for bulk data copy

A data storage library system and a method for storing, and maintaining and tracking synchronism between, multiple copies of identifiable data volumes between hosts and a plurality of data storage libraries, and transparent to the hosts. The library controller of each library provides an updatable synchronization token directly associated with each data volume. A plurality of directors are provided, each separate from and coupled to the hosts and each separate from and coupled to each data storage library. Each director responds to ones of separate, partitioned access addresses addressed by the hosts. The responding director supplies each data volume supplied from a host to all of the data storage libraries, and updates each synchronization token directly associated with the supplied data volume. Thus, the directors store duplicate copies of the data volume in the data storage libraries without involvement by the host. The currency of the data volumes are each tracked by means of the directly associated synchronization token, and the synchronization token is not tracked by the host nor is a central tracking database required.

Storing and tracking multiple copies of data in a data storage library system

A data storage library subsystem and a method for storing, and maintaining and tracking synchronism between, multiple copies of identifiable data volumes between hosts and a plurality of data storage libraries, and transparent to the hosts. The library controller of each library provides an updatable synchronization token directly associated with each data volume. A plurality of directors are provided, each separate from and coupled to the hosts and each separate from and coupled to each data storage library. Each director responds to ones of separate, partitioned access addresses addressed by the hosts. The responding director supplies each data volume supplied from a host to all of the data storage libraries, and updates each synchronization token directly associated with the supplied data volume. Thus, the directors store duplicate copies of the data volume in the data storage libraries without involvement by the host. The currency of the data volumes are each tracked by means of the directly associated synchronization token, and the synchronization token is not tracked by the host nor is a central tracking database required.

Storing and tracking multiple copies of data in data storage libraries

A method and system for enhancing the efficiency of data accessing within a storage subsystem which is coupled to a host system via a storage subsystem controller and a data channel. The storage subsystem controller preferably includes a tracked cyclic storage device which has multiple disks which are rotatable about a single spindle. Recording tracks within each disk are then accessed utilizing multiple switchable transducer heads. A signal transmitted from the host system is utilized to define a sequence in which a group of recording tracks are to be accessed. That signal is then utilized to create a transducer head switching table within the storage subsystem controller which lists each recording track to be accessed and an associated control parameter for selecting a particular transducer head to be utilized to access a subsequent recording track. Each time the end of an accessed recording track is encountered, the transducer head switching table is accessed and the control parameter associated with that track is accessed and coupled to the tracked cyclic storage device transducer head switch in order to select a subsequent recording track for access. In this manner, a plurality of tracks may be accessed in any desired order. A pointer is established into the transducer head switching table at the listing of an initially accessed recording track and access may be terminated when that pointer is encountered.

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Tucson, AZ, United States of America

Dean Lee Hanson