Abstract: A system and method for dynamic redistribution of parity groups is described. The system and method for dynamic redistribution of parity groups operates on a computer storage system that includes a plurality of disk drives for storing parity groups. Each parity group includes storage blocks. The storage blocks include one or more data blocks and a parity block that is associated with the data blocks. Each of the storage blocks is stored on a separate disk drive such that no two storage blocks from a given parity set reside on the same disk drive. The computer system further includes a redistribution module to dynamically redistribute parity groups by combining some parity groups to improve storage efficiency.

Abstract: Peer-to-peer redundant file server system and methods include clients that determine a target storage provider to contact for a particular storage transaction based on a pathname provided by the filesystem and a predetermined scheme such as a hash function applied to a portion of the pathname. Servers use the same scheme to determine where to store relevant file information so that the clients can locate the file information. The target storage provider may store the file itself and/or may store metadata that identifies one or more other storage providers where the file is stored. A file may be replicated in multiple storage providers, and the metadata may include a list of storage providers from which the clients can select (e.g., randomly) in order to access the file.

Abstract: Disk based emulation of tape libraries is provided with features that allow easier management and administration of a backup system and also allow increased flexibility to both archive data on tape at a remote location and also have fast restore access to archived data files. Features include automatic emulation of physical libraries, and the retention and write protection of virtual tapes that correspond to exported physical tapes.

Abstract: A system and method for dynamic redistribution of parity groups is described. The system and method for dynamic redistribution of parity groups operates on a computer storage system that includes a plurality of disk drives for storing parity groups. Each parity group includes storage blocks. The storage blocks include one or more data blocks and a parity block that is associated with the data blocks. Each of the storage blocks is stored on a separate disk drive such that no two storage blocks from a given parity set reside on the same disk drive. The computer system further includes a redistribution module to dynamically redistribute parity groups by combining some parity groups to improve storage efficiency.

Abstract: Systems and methods for replicating data from a first site to a second site remote from said first site are described. An embodiment includes storing compressed data on a hard disk appliance, reading said data without decompressing said data, sending said data over a wide-area-network (WAN) in a compressed state, and storing said data on a second hard disk appliance remote from said first hard disk appliance in its compressed state without performing an additional compression operation.

Abstract: Systems and methods for replicating data from a first site to a second site remote from said first site are described. An embodiment includes storing compressed data on a hard disk appliance, reading said data without decompressing said data, sending said data over a wide-area-network (WAN) in a compressed state, and storing said data on a second hard disk appliance remote from said first hard disk appliance in its compressed state without performing an additional compression operation.

Abstract: A system and method for dynamic redistribution of parity groups is described. The system and method for dynamic redistribution of parity groups operates on a computer storage system that includes a plurality of disk drives for storing parity groups. Each parity group includes storage blocks. The storage blocks include one or more data blocks and a parity block that is associated with the data blocks. Each of the storage blocks is stored on a separate disk drive such that no two storage blocks from a given parity set reside on the same disk drive. The computer system further includes a redistribution module to dynamically redistribute parity groups by combining some parity groups to improve storage efficiency.

Abstract: A system and method for dynamic redistribution of parity groups is described. The system and method for dynamic redistribution of parity groups operates on a computer storage system that includes a plurality of disk drives for storing parity groups. Each parity group includes storage blocks. The storage blocks include one or more data blocks and a parity block that is associated with the data blocks. Each of the storage blocks is stored on a separate disk drive such that no two storage blocks from a given parity set reside on the same disk drive. The computer system further includes a redistribution module to dynamically redistribute parity groups by combining some parity groups to improve storage efficiency.

Abstract: A data protection and storage system includes an array of disk drives for data storage. Data is received for storage on the disk drive via an interface that is configured to emulate a tape drive interface. A virtual tape data structure is created and stored on the disk drives. The allocated capacity of the virtual tape is dynamically and transparently alterable in response to data storage demand within the virtual tape.

Abstract: A data protection and storage system includes an array of disk drives for data storage. Data is received for storage on the disk drive via an interface that is configured to emulate a tape drive interface. A virtual tape data structure is created and stored on the disk drives. The allocated capacity of the virtual tape is dynamically and transparently alterable in response to data storage demand within the virtual tape.

Abstract: A system for sharing block data includes a non-removable device for storing block data (e.g. a hard drive) that is networked with a plurality of computers. Each computer can initiate discovery commands and read/write commands, and transmit these commands over the network to the non-removable storage device. Computer commands are intercepted and processed by a logical algorithm program at the storage device. One function of the logical algorithm program is to instruct each computer to treat the non-removable block storage device as a removable block device. Because the computers treat the storage device as a removable block device, they relinquish control of the device (after use) to other computers on the network. The logical algorithm program also functions to allocate temporary ownership of the block storage device to one of the computers on the network and passes temporary ownership from computer to computer on the network.

Abstract: A system for sharing block data includes a non-removable device for storing block data (e.g. a hard drive) that is networked with a plurality of computers. Each computer can initiate discovery commands and read/write commands, and transmit these commands over the network to the non-removable storage device. Computer commands are intercepted and processed by a logical algorithm program at the storage device. One function of the logical algorithm program is to instruct each computer to treat the non-removable block storage device as a removable block device. Because the computers treat the storage device as a removable block device, they relinquish control of the device (after use) to other computers on the network. The logical algorithm program also functions to allocate temporary ownership of the block storage device to one of the computers on the network and passes temporary ownership from computer to computer on the network.

Abstract: A data protection and storage system includes an array of disk drives for data storage. Data is received for storage on the disk drive via an interface that is configured to emulate a tape drive interface. A virtual tape data structure is created and stored on the disk drives. The data structure includes entry tables that form a linked list where each contain links to other entry tables and information defining data storage sectors allocated to records associates a virtual tape.

Abstract: A block level data snapshot system uses agents to convert block level file commands from devices such as computer workstations intended for block level devices such as hard disks. The block level file commands are converted into instructions for a node based snapshot data system for taking snapshots at the block level. By converting the block level file commands into instructions suitable for the node based snapshot system, snapshots are able to be taken at the block level, which allows for disk storage savings and speed enhancements. One resultant feature is that the block level data snapshot system can be used as a block level storage device for one or more workstations thus allowing relatively simple integration of a snapshot system with existing workstations.

Abstract: The present invention comprises a magnetic recording system including a partial response, maximum likelihood recording channel incorporating fixed frequency read signal sampling and a digital timing control loop. Such a system is especially suitable in magnetic tape recording systems having a high degree of media speed variation during the read and write processes.

Abstract: A digital data recording channel which uses variable rate encoding. The encoder monitors an input bit stream for sequences associated with selected readback characteristics, and inserts one or more bits where desirable to improve the characteristics of the stored bit stream.

Abstract: An apparatus for encoding digital data for storage on a data storage medium includes a non-deterministic randomizer code generator. The randomizer code generator may select different randomizer codes for different portions of the data to be stored. The randomizer code used to randomize a given portion of the data may be stored on the media for use in subsequent data retrieval.

Abstract: A media element library includes two linear arrays of media elements. Positioned between the two media element arrays is a linearly extending track on which a media element transfer carriage is mounted. The track is split into two segments, with one of the segments being rotatable. The rotatable segment pivots through 180 degrees so that the media element transfer carriage can access both arrays of media elements as well as tape drives provided within the library.