Abstract: 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.

Abstract: Identifying most recent redundant copies of identifiable data volumes stored in a plurality of data storage libraries which are coupled to a plurality of directors. To update a data volume, an initiating director attempts to set a current token “inconsistent” flag to potentially down level copies of the data volume on each lagging library. Upon failing to receive notification of any successful setting of the current token “inconsistent” flag from any of the lagging libraries, the director forwards the request to the other directors, which attempt to set the current token “inconsistent” flag for the volume at any lagging library from which no notification has been received. Upon all of the other directors responding to the initiating director, and upon the other directors indicating failure to set the “inconsistent” flag at the lagging library, all the directors list the volume and a new token as an entry in a “hot token” list.

Abstract: A file translation system and a physical information and extensions file for an intermediary controller is disclosed. The file translation system that allow a host computer to directly access data from a different host type without moving the actual data. The physical information and extension file provides information concerning the location of data and the file system the host is viewing. The intermediary controller is disposed between a legacy disk controller for an originating host of a first type and an open system host. The intermediary controller emulates a virtual storage device using a virtual device file system, wherein the virtual device file system mapping data stored in a storage device by the originating host to objects in a root directory in the virtual device file system.

Abstract: A converter system that allows a host system using a first interface to use a second storage using a second interface. The invention provides a method to allow an ECKD MVS DASD storage using an ESCON interface to be used by an open system using a SCSI-type interface without changes to the ESCON storage or the open storage interfaces. The method also permits the SCSI-type interfaced open system to be physically located greater than 25 meters from the ESCON storage system. The method involves mapping the SCSI-type interface data and commands into parameters used and understood by the ESCON storage. The invention may also be implemented to provide a digital data storage medium containing the method of the invention and a digital apparatus capable of executing the invention.

Abstract: In an data storage system, a volume transform filter is employed in conjunction with a RAID array manager to maintain logical volumes entirely on corresponding physical data storage volumes while maintaining parity information on a dedicated parity storage volume. This is achieved by modifying data access commands received from a host such that forwarding the modified commands to the RAID array manager in effect "tricks" the RAID array manager into maintaining the logical volumes without striping. This system provides data allocation with standalone data and parity storage volumes, which are easily exportable for convenient use in data storage libraries.