Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.