Abstract: A technique includes reading or writing at least one unit of data to or from a sequential access storage medium, which has a physical dimension that is subject to expansion and contraction; and reading or writing a value that indicates the physical dimension.

Abstract: A method of writing data to a tape on which during a write operation successive data unit groups that comprise a plurality N of data units are written across the tape as N track portions to form N data tracks that extend in a lengthways direction of the tape. The method includes identifying data units written during the write operation that need to be rewritten and writing a rewrite data unit group that contains data units identified as needing to be rewritten. The rewrite data unit group has N track portions written across the tape to form a part of the data tracks. The N track portions contain N-n data units identified as needing to be rewritten and data unit identifier information comprising respective data unit identifiers for the N-n data units contained in at least one list of data unit identifiers. N and n are positive integers.

Abstract: Data storage and retrieval methods and apparatus are provided for facilitating data de-duplication for serial-access storage media such as tape. During data storage, input data is divided into a succession of chunks and, for each chunk, a corresponding data item is written to the storage media. The data item comprises the chunk data itself where it is the first occurrence of that data, and otherwise comprises a chunk-data identifier identifying that chunk of subject data. To facilitate reconstruction of the original data on read-back from the storage media a cache (50) is used together with a database (35R), stored on the media, that includes for each duplicated chunk, the location of the corresponding chunk of subject data.

Abstract: A method and apparatus for writing data to a tape is disclosed. A plurality of data segments are written onto a tape simultaneously. Any data segments written to the tape that needs to be rewritten are identified. Each data segment that needs to be re-written is accumulated. The accumulated data segments are written to tape when a full set of data segments have been accumulated. The re-written data segments each have a first field in a header that designates itself and a second field in the header that designates a second re-written data segment.

Abstract: A technique includes compressing or decompressing data using a relative displacement of a location of a data pattern.

Abstract: A data processing apparatus comprises a monolithic integrated circuit having a data processor, a non-volatile memory storing at least one security code, and at least one interface at the boundary of the integrated circuit via which communication with the data processor can occur. Processing by the data processor of data received at the at least one interface is controlled by the at least one security code.

Abstract: A data transfer device for transferring data to a removable data storage item. The data transfer device receives content data to be stored to the removable data storage item, encrypts the content data using an encryption key, and transforms at least one of predetermined reference data and the encryption key. The data transfer device also encrypts the transformed predetermined reference data using the encryption key or encrypts the predetermined reference data using the transformed encryption key, and then stores the encrypted content data and the encrypted transformed/predetermined reference data to the removable data storage item.

Abstract: A method and apparatus for writing data to a tape is disclosed. A plurality of data tracks are written onto a tape simultaneously. Any data tracks written to the tape that needs to be rewritten are identified. Each re-write unit that contains a data track that needs to be re-written is accumulated. The accumulated rewrite units are written to tape when a full set of rewrite units have been accumulated.

Abstract: A technique includes compressing or decompressing data using a relative displacement of a location of a data pattern.

Abstract: A history buffer for use in adaptive lossless data compression comprises a plurality of memory locations. The memory locations are partitioned into two or more segments, each segment configured to detect a match sequence independently of the other segments. Control logic is provided for controlling the detection of match sequences between the two or more segments.

Abstract: A method and apparatus for writing data to a tape is disclosed. A plurality of data segments are written onto a tape simultaneously. Any data segments written to the tape that needs to be rewritten are identified. Each data segment that needs to be re-written is accumulated. The accumulated data segments are written to tape when a full set of data segments have been accumulated. The re-written data segments each have a first field in a header that designates itself and a second field in the header that designates a second re-written data segment.

Abstract: A method and apparatus for writing data to a tape is disclosed. A plurality of data tracks are written onto a tape simultaneously. Any data tracks written to the tape that needs to be rewritten are identified. Each re-write unit that contains a data track that needs to be re-written is accumulated. The accumulated rewrite units are written to tape when a full set of rewrite units have been accumulated.

Abstract: A history buffer for use in adaptive lossless data compression comprises a plurality of memory locations. The memory locations are partitioned into two or more segments, each segment configured to detect a match sequence independently of the other segments. Control logic is provided for controlling the detection of match sequences between the two or more segments.

Abstract: Data storage and retrieval methods and apparatus are provided for facilitating data de-duplication for serial-access storage media such as tape. During data storage, input data is divided into a succession of chunks and, for each chunk, a corresponding data item is written to the storage media. The data item comprises the chunk data itself where it is the first occurrence of that data, and otherwise comprises a chunk-data identifier identifying that chunk of subject data. To facilitate reconstruction of the original data on read-back from the storage media a cache (50) is used together with a database (35R), stored on the media, that includes for each duplicated chunk, the location of the corresponding chunk of subject data.

Abstract: A data transfer device for transferring data to a removable data storage item. The data transfer device encrypts data to be stored using an encryption key, and additionally encrypts a copy of the encryption key using the encryption key. The data transfer device then stores the encrypted data and the encrypted encryption key to the removable data storage item.

Abstract: A data transfer device for storing data to a removable data storage item, wherein data are received as records and encrypted by the data transfer device prior to storage. The data transfer device encrypts a first portion of the records using a first encryption key and a second portion of the records using a second encryption key. The encrypted records are then stored to the removable data storage item as a plurality of data blocks, each data block comprising one or more encrypted records, wherein records in a respective data block are encrypted using only a respective one of the encryption keys.

Abstract: A data transfer system comprising a host device and a data transfer device. The host device generates an encryption key based upon information unique to a removable data storage item onto which data are to be stored. The encryption key is then delivered by the host device to the data transfer device. Data to be stored are encrypted by the data transfer device using the encryption key.

Abstract: A data processing apparatus comprises an integrated circuit containing a data processor and a non-volatile store storing at least one security code. A first memory external to the integrated circuit stores data, the data being cryptographically protected in a first format. A second memory external to the integrated circuit is provided for storing data. The apparatus is arranged to transfer data from the first memory via the integrated circuit to the second memory to be accessed by the data processor from the second memory. The integrated circuit is arranged to validate during the transfer the data read from the first memory using a security code stored in the non-volatile store. If the data is validated, cryptographic protection is applied in a second format to the validated data using a security code stored in the non-volatile store. The protected data is stored in the second memory in the second format.

Abstract: A data processing apparatus comprises a monolithic integrated circuit having a data processor, a non-volatile memory storing at least one security code, and at least one interface at the boundary of the integrated circuit via which communication with the data processor can occur. Processing by the data processor of data received at the at least one interface is controlled by the at least one security code.

Abstract: A data transfer device for transferring data to a removable data storage item. The data transfer device receives content data to be stored to the removable data storage item, encrypts the content data using an encryption key, and transforms at least one of predetermined reference data and the encryption key. The data transfer device also encrypts the transformed predetermined reference data using the encryption key or encrypts the predetermined reference data using the transformed encryption key, and then stores the encrypted content data and the encrypted transformed/predetermined reference data to the removable data storage item.