Storage Technology Corporation

Alan Ray Sutton

Stephen Henry Blendermann

Robert J Raicer

L Michael Anderson

Clayton E Ruff

William G Kefauver

Charles Allen Milligan

Michael Lawrence Leonhardt

Ronald W Korngiebel

Richard John Defouw

Kurt G Schumacher

Kevin L Merkley

A method for selectively controlling reutilization of space in a virtual tape system (VTS) having a buffer and a multiple volume tape cartridge includes transferring data volume files to the VTS. The buffer transfers the data making up these files as virtual tape volumes (VTVs) to different locations of the cartridge for storage. A file is selectively designated for the VTS to delete from storage after a date included with the file has elapsed by deleting the VTVs corresponding to the file from the cartridge to reuse space of the cartridge. The method includes detecting if a file transferred as VTVs to the cartridge has been designated for deletion. The VTS is prohibited from deleting the file after the date has elapsed if the file was not designated for deletion and is allowed to delete the file after the date has elapsed if the file was not designated for deletion.

Data storage management method for selectively controlling reutilization of space in a virtual tape system

A data storage system for storing data for a host processor includes physical data storage devices each having data storage attributes and an outboard storage manager. The outboard storage manager is operable with the physical data storage devices for presenting to the host processor a virtual data storage image having a desired data storage attribute for a particular data storage application by organizing the physical data storage devices in an arrangement suitable for providing the desired data storage attribute irrespective of the data storage attributes of the physical data storage devices such that the combined physical data storage device arrangement emulates the virtual data storage image. The outboard storage manager is operable to transfer data between the host processor and the organized physical data storage device arrangement via the virtual data storage image.

Outboard data storage management system and method

The present invention provides a virtual automated cartridge system (ACS) and data storage device management method which incorporates a temporary data buffer arrangement between multiple user systems and conventional physical data storage devices. The temporary data buffer arrangement emulates a compatible physical data storage device when accessed by each of the user systems, but allows simultaneous allocation of different users to access to read and write data to the temporary data buffer. A control processor automatically transfers data stored in the temporary data buffer arrangement to one of the physical data storage devices when allocation to a user has ended.

Data storage management system and method

A method for selectively controlling reutilization of data space in a virtual tape system is provided which allows a user to designate whether data from a scratched virtual volume can be automatically deleted without any further action on the part of the user. This allows a user to selectively choose to create a safety net by which expired data could still be retrieved if so desired, while also minimizing the impact of such a safety net feature on the overall efficiency in space management otherwise provided by the virtual tape system.

Method for controlling reutilization of data space in virtual tape system

A caching method for selecting variable size data blocks for replacement or removal from a cache includes determining the size and the unreferenced time interval of each block in the cache. The size of a block is the amount of cache space taken up by the block. The unreferenced time interval of a block is the time that has elapsed since the block was last accessed, and may be determined using a least recently used (LRU) algorithm. The recall probability of each block in the cache is then determined. The recall probability of a block is a function of its unreferenced time interval and possibly size and other auxiliary parameters. The caching method then determines a quality factor (q) for each block. The (q) of a block is a function of its recall probability and size. The caching method concludes with removing from the cache the block with the lowest (q). Various formulas or methods for determining the quality factor may be chosen so as to minimize the quantity of data that must be staged, minimize mean response time, or maximize the cache hit ratio.

Caching method for selecting data blocks for removal from cache based on recall probability and size

The present invention provides a method for selectively storing duplicate copies of a virtual data volume file onto more than one multiple volume cartridge (MVC) based upon a copy indicator provided with a data volume file at the meta data file level. If access is subsequently lost to the main MVC as a result of hardware or tape failure, any copied data stored thereon is automatically recovered by accessing an MVC holding a copy of the data volume file. Thus, the amount of data which could be possibly lost is minimized without otherwise compromising the efficiency and flexibility provided by a multiple virtual volume data storage arrangement.

Method for selectively storing redundant copies of virtual volume data on physical data storage cartridges

A method for verifying availability of reusable data space on a selected virtual scratch tape in a virtual tape system utilizes volume label information routinely maintained in an external tape inventory management arrangement to generate labels separate from the actual volume labels stored on a corresponding tape. The volume labels are generated in a format compatible for input to an external tape management system after the selected virtual scratch tape has been mounted on a virtual tape drive. The &ldquo;on-the-fly&rdquo; generation of the separate volume labels based on preexisting label information allows the present invention to significantly reduce processing time and needless data transfers typically required to verify whether a scratch tape can in fact be reused, thereby increasing overall efficiency in data storage management and storage space utilization.

Method for verifying availability of data space in virtual tape system

The present invention provides a method for selectively reclaiming fragmented space on a multiple volume cartridge (MVC) device using a cost-benefit type analysis to determine whether making the fragmented space useable justifies moving all nonexpired data volume sets to another MVC. The present invention analyzes the allocation of space on the MVC to determine the location and size of any gaps between nonexpired data volume sets. Any gaps appearing at the end of the MVC are automatically reallocated for subsequent use. Any gaps appearing between nonexpired data volume sets are analyzed to determine whether the size and location meet predetermined criteria before moving any of the nonexpired data volume sets. In addition, the present invention allows selective movement of less than all of the nonexpired data volume sets if the size of the separating gap is larger than any nonexpired data volume sets appearing after the gap.

Method for reclaiming fragmented space on a physical data storage

Virtual automated cartridge system

The present invention provides a method for selectively storing data files on a multiple volume cartridge (MVC) device which maximizes the likelihood of gaps in stored data appearing at the end of a cartridge. All incoming data files are initially stored in a virtual disk buffer, and checked to determine time of expiration. The expiration information is then used to reorder the virtual data volume files when placed on the MVC device so that the last to expire is stored first, and the first to expire is stored last.

Method for optimized placement of virtual volumes on a physical cartridge

A tiered communications service which utilizes multiple methods of communication and provides the ability for different host computer systems to pass dam, unconcerned with the type of communications medium used by the service. Each method of communication is ranked according to its preference within the service. When the communications service encounters an error while attempting to send data to another host system, it performs an automatic switch to the method with the next lower preference which is available for use. The service sends notification to the other system of the change in communications method used and which method to start using, then continues sending the data. The communications method may be switched to a higher or lower preferred method explicitly by operator command, which also sends notification to the other systems of a change in method. Each host system has the ability to communicate with other host systems via various communications methods, depending on the methods defined to the service. A host system can communicate with a second host system using one communications method and communicate with a third host computer system using a different communications method. To communicate between any two host systems, the service utilizes the highest preferred common communications method available for use, except when changed by operator command.

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Boulder, CO, United States of America

Alan Ray Sutton