Abstract: An authenticated encryption method and apparatus are described in which plaintext data is encrypted, using a secret key, to form ciphertext data. A message authentication code, MAC, is also formed in dependence on a combination of the ciphertext data and data characteristic of the plaintext data. The ciphertext data and the MAC are then output, for example, for storage to a storage medium. In a preferred embodiment a block cipher operating in GCM mode is adapted to cause the stored message authentication code to be dependent on the plaintext data.

Abstract: A data reader is arranged to read data from a data-holding medium, said data being arranged into a plurality of data items each containing user data and non-user data, with said non-user data including one or more synchronisation fields. The data reader has a read head for reading a channel of said data-holding medium to generate a data signal comprising said data items, and processing circuitry arranged to receive and process said data signals to detect synchronisation fields, including qualifying the detection of the synchronisation fields to tolerate one or more errors in those synchronisation fields. This means that the synchronisation fields can be detected more reliably, so that more of the user data is recovered.

Abstract: A linear tape data storage device comprises a read head and a write head; a tape transport mechanism for transporting the linear tape data storage medium across the read head and the write head, the device being operated according to a predefined tape format; a DRAM buffer memory for storing data received during a write or a read operation; and error protection means configured to protect said data from soft errors generated by said buffer memory wherein the protection means comprises means for checking parity generated within the tape format itself. In the preferred embodiment the tape format used is the Linear Tape Open (LTO) format.

Abstract: A data reader is arranged to read data comprising user data 30 and non-user data 32, 34 written across at least two channels of a data-holding medium 10, said data being arranged into a plurality of data items 26 each containing user data and non-user data, with said non-user data holding information relating to said user data, including write pass number information, and data items written across the said channels at the same time being identified as a set of data items, said data reader holding a current write pass number and having a read head 12 for reading a respective said channel of said data-holding medium 10 to generate a data signal comprising said data items, and processing circuitry 258, 280 arranged to receive and process said data signals of a set of data items, including processing said write pass number information of each of said data items in said set, and causing updating of said current write pass number held by said data reader on the basis of the write pass number information of said dat

Abstract: Data from a host computer is buffered, transferred to a logical formatter, compressed and converted to a format suitable for storage on a magnetic tape before being arranged and written sequentially into a main buffer where parity bytes are added as each row of a dataset is written. A physical formatter takes the data sequentially from the main buffer and writes them as codeword quadsets in plural tape tracks. A determination of whether each codeword quadset is acceptably recorded is made by evaluating each codeword quadset for header and codeword quadset pair errors and combining the evaluations.

Abstract: There is disclosed a method of accurately locating an append point along a length of linear tape data storage medium, comprising entering a search mode searching for an absolute code word quad set number, and having found the absolute code word quad set number, entering an interrupt mode for control of tape transport, followed by a write mode to write data at a data set containing the absolute code word quad set number.

Abstract: A data reader reads a medium holding user and non-user data that holds information relating to the user data. The reader has a read head that generates a data signal comprising user and non-user data. The user data is arranged into plural sets interspersed with the non-user data that identifies the user data within the sets. Processing circuitry receives and processes the data signal and obtains the user data from the data signal by using the non-user data to identify the user data within the data signal. The data reader is particularly suitable in situations having re-writes and overwrites.

Abstract: Data are written to plural parallel data tracks of a data storage medium by arranging a data stream into plural streams of data sets. Each stream of data sets is allocated to a corresponding respective group of parallel data tracks. A plurality of the data sets are written to the plural data track groups, such that in each data stream, each data set commences at substantially the same position along a length of the linear data storage medium, as a data set of another of the streams.

Abstract: A data reader is arranged to read data comprising user data and non-user data written across at least two channels of a data-holding medium, the data being arranged into a plurality of data items each containing user data and non-user data, with the non-user data holding information relating to the user data, including a header with information relating to the user data and header error detection information, and data items written across the channels at the same time being identified as a set of data items.

Abstract: A data reader is arranged to read data comprising user data 30 and non-user data 32, 34 written across at least two channels of a data-holding medium 10, said data being arranged into a plurality of data items 26 each containing user data and non-user data, with said non-user data holding information relating to said user data, said data reader having a read head 12 for reading a respective said channel of said data-holding medium 10 to generate a data signal 14 comprising said data items, and processing circuitry 250 arranged to receive and process said data signals to identify a set CCPset1 of said data items written at the same time onto different said channels. Identifying a set of data items written at the same time gives rise to the possibility of correcting header information for the data items in a set.

Abstract: A method for recovering user data from a host device stored on a data storage medium where a said data may become corrupted during a read operation comprises: performing a read operation to read at least one encoded data fragment of said plurality of encoded data fragments from said data storage medium; storing status data indicating whether said at least one data fragment was correctly read; writing said read at least one data fragment to a buffer memory; attempting to decode said at least one encoded data fragment in said buffer memory wherein if said attempted decoding is unsuccessful then said method further comprises the steps of: re-reading incorrectly read encoded data fragments from said data storage medium; and attempting to decode said encoded data fragments located in said buffer memory.

Abstract: A linear tape data storage device comprises a read head and a write head; a tape transport mechanism for transporting the linear tape data storage medium across the read head and the write head, the device being operated according to a predefined tape format; a DRAM buffer memory for storing data received during a write or a read operation; and error protection means configured to protect said data from soft errors generated by said buffer memory wherein the protection means comprises means for checking parity generated within the tape format itself. In the preferred embodiment the tape format used is the Linear Tape Open (LTO) format.

Abstract: A data reader is arranged to read data from a data-holding medium, said data being arranged into a plurality of data items each containing user data and non-user data, with said non-user data including one or more synchronisation fields. The data reader has a read head for reading a channel of said data-holding medium to generate a data signal comprising said data items, and processing circuitry arranged to receive and process said data signals to detect synchronisation fields, including qualifying the detection of the synchronisation fields to tolerate one or more errors in those synchronisation fields. This means that the synchronisation fields can be detected more reliably, so that more of the user data is recovered.

Abstract: A data reader is arranged to read data comprising user data and non-user data written across at least two channels of a data-holding medium, the data being arranged into a plurality of data items each containing user data and non-user data, with the non-user data holding information relating to the user data, including a header with information relating to the user data and header error detection information, and data items written across the channels at the same time being identified as a set of data items.

Abstract: A data reader arranged to read a data-holding medium 10 containing both user 30 and non-user 32, 34 data, said non-user data 32, 34 holding information relating to said user data 30, said data reader comprising at least one read head 12 arranged to read the data-holding medium 10 and generate a data signal 14 comprising user data and non-user data, said user data being arranged into a plurality of sets interspersed with said non-user data, said non-user data being arranged to identify said user data within said sets, processing circuitry 8 being arranged to receive and process said data signal 14 and obtain said user data 30 from said data signal 14 using said non-user data 32, 34 to identify said user data 30 within said data signal 14. The data reader is particularly suitable for use in tape drives, and/or in situations in which re-writes, and overwrites of data occur.

Abstract: A data reader is arranged to read data comprising user data 30 and non-user data 32, 34 written across at least two channels of a data-holding medium 10, said data being arranged into a plurality of data items 26 each containing user data and non-user data, with said non-user data holding information relating to said user data, said data reader having a read head 12 for reading a respective said channel of said data-holding medium 10 to generate a data signal 14 comprising said data items, and processing circuitry 250 arranged to receive and process said data signals to identify a set CCPset1 of said data items written at the same time onto different said channels. Identifying a set of data items written at the same time gives rise to the possibility of correcting header information for the data items in a set.

Abstract: A system for transferring data from a host computing system 10 to a magnetic tape cartridge 12. Data from the host computing system 10 is buffered in a burst buffer 14 before transfer to a logical formatter 16, where data is compressed and converted to a format suitable for storage on the magnetic tape cartridge 12. The logical formatter 16 arranges the data into ‘datasets. The datasets are written sequentially into a main buffer 24 and, as each row of a dataset is written into the main buffer 24, parity bytes (Reed-Solomon) are added.

Abstract: A data reader is arranged to read data comprising user data 30 and non-user data 32, 34 written across at least two channels of a data-holding medium 10, said data being arranged into a plurality of data items 26 each containing user data and non-user data, with said non-user data holding information relating to said user data, including write pass number information, and data items written across the said channels at the same time being identified as a set of data items, said data reader holding a current write pass number and having a read head 12 for reading a respective said channel of said data-holding medium 10 to generate a data signal comprising said data items, and processing circuitry 258, 280 arranged to receive and process said data signals of a set of data items, including processing said write pass number information of each of said data items in said set, and causing updating of said current write pass number held by said data reader on the basis of the write pass number information of said dat

Abstract: There is disclosed a method of accurately locating an append point along a length of linear tape data storage medium, comprising entering a search mode searching for an absolute code word quad set number, and having found the absolute code word quad set number, entering an interrupt mode for control of tape transport, followed by a write mode to write data at a data set containing the absolute code word quad set number.