Hewlett-packard Company

Hewlett-packard Development Company, L.p.

Jeff J Kato

David J Van Maren

David W Ruska

Kelly John Reasoner

Gregg S Schmidtke

Peter Thomas Camble

Jeffrey P Tobin

Carl B Lantz

A method for providing data storage capacity on demand comprises disabling a set of slot elements and data transfer elements of a data library disallowing access to the disabled set by end users of the library, partitioning at least a portion of a set of active data media storage slot elements and active data transfer elements of the data library, exclusive of the disabled set, into partitions for use by the end users; and redefining the sets in response to changes in storage capacity rights of the end users.

Method for using partitioning to provide capacity on demand in data libraries

Storage media cartridge handling apparatus is disclosed that comprises: a frame to support first and second laterally spaced arrays of cartridge access locations extending in a front-back direction, and at least one laterally extending further array of cartridge access locations, the cartridge access locations facing inwardly of the frame; an up-down drive arrangement disengageably engageable with an accessor carriage to move the carriage up and down in a region between the first and second arrays, to access locations in the first, second and further arrays; and at least one lateral displacement path within the frame along which the carriage can exit and enter the frame laterally. A storage media cartridge library and an accessor carriage are also disclosed.

Storage media cartridge handling apparatus with up-down drive arrangement disengageable with accessor carriage

A tape packet assembler/disassembler (TPAD) for a tape drive accumulates host-transmitted records, which may or may not be blocked by the host. The accumulated host-transmitted records are combined into packets comprising a data portion made up of data blocks and of a trailer portion made up of table entries describing how to disassemble the packet. Host-transmitted commands to write a tape mark are intercepted by the TPAD and replaced by corresponding information in the trailer. Packets are accumulated in a buffer in the TPAD, and are written to the tape drive when the buffer becomes full, or upon a command from the host to reposition the tape, such as rewind. The interblock gaps that would ordinarily separate the host-transmitted records now separate packets, resulting in a considerable increase in the efficiency of tape utilization. The TPAD maintains in the trailer various pointers to assist in forward and back spacing by file and records. It also can automatically and adaptively compress and decompress the user's data. To assist in this it also maintains in the trailer information identifying data blocks containing a dictionary reset.

High capacity tape drive transparently writes and reads large packets of

A logic circuit in an integrated circuit implementation of an adaptive data compression algorithm which uses a RAM to store dictionary entries. The logic circuit generates predetermined codewords for single-character strings without accessing the dictionary. The logic circuit also generates single-character strings for corresponding codewords without accessing the dictionary.

Data compression dictionary access minimization

A tape packet assembler/disassembler (TPAD) for a tape drive accumulates host-transmitted records, which may or may not be blocked by the host. The accumulated host-transmitted records are combined into packets comprising a data portion made up of data blocks and a trailer portion made up of table entries describing how to disassemble the packet. Host-transmitted commands to write a tape mark are intercepted by the TPAD and replaced by corresponding information in the trailer. Packets are accumulated in a buffer in the TPAD, and are written to the tape drive when the buffer becomes full, or upon a command from the host to reposition the tape, such as rewind. The interblock gaps that would ordinarily separate the host-transmitted records now separate packets, resulting in a considerable increase in the efficiency of tape utilization. The TPAD maintains in the trailer various pointers to assist in forward and back spacing by file and records. It also can automatically and adaptively compress and decompress the user's data. To assist in this it also maintains in the trailer information identifying data blocks containing a dictionary reset.

A data compression system implementing expansion protection employs one or more pairs of FIFOs to compare the lengths of raw and processed versions of a block of received data. The shorter version is transmitted so that the data transmitted by the data compression system is at most negligibly expanded relative to the system input. A code is inserted in the output stream to indicate the beginning of the transmission of a raw data block so that a receiving or retrieving system can determine whether the data following needs to be decompressed or not. Further codes can be injected to indicate a switch from raw data to processed data in the output of the compression system.

Data compression system with expansion protection

An adaptive data compression system is reset when performance drops below a predetermined threshold to permit greater compression of long files with evolving distributions of symbol combinations. The compression system uses a resettable dictionary in which initially unassigned codes are strategically assigned to symbol combinations as they are encountered in the data stream. The difference between the bit-lengths of corresponding lengths of the compressor input and output is compared with a value representing a predetermined performance threshold. The dictionary can be reset if the actual performance falls below the performance threshold. The reset can be inhibited while the dictionary is less than half-full to ensure that performance measures are statistically significant. However, if the performance is such that data expansion is occurring, reset is not so delayed.

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Greeley, CO, United States of America

Jeff J Kato