Abstract: Data storage apparatus comprises a tape drive and a tape cartridge, the tape cartridge having a data storage tape on which write-once-read-many (WORM) data is stored. The data storage apparatus is controlled by providing a format command to the tape drive commanding a formatting operation that conditions the tape for erasure or overwriting of the WORM data. A format command key is provided with the format command to be compared with a key recorded in the cartridge. The format command is enabled in dependence upon the comparison between the format command key and the recorded key.

Abstract: A method is provided of detecting if WORM data has been tampered with, the data having been recorded in a sequence of data sets. Each data set includes a write pass value and the write pass values are incremented at intervals in the sequence according to a predetermined rule providing that the write pass values are incremented each time a predetermined number of the data sets has occurred in the sequence. The data sets are read in sequence and the write pass value of each data set is compared with the write pass value of the preceding data set. An indication is made if the write pass value of any of the data sets differs from the write pass value of the preceding data set by an amount that breaches the predetermined rule.

Abstract: Briefly described, one embodiment of a method of recording data in a sequence of data sets onto a data recording medium having a recording capacity up to an end of medium position includes the following steps: deriving a logical count of the amount of data recorded on the recording medium, and comparing the logical count to a reference value to generate a warning of an approach to the end of medium position. Other methods and systems are also provided.

Abstract: A data storage apparatus comprises a tape cartridge having a cartridge memory which is configured to store data representing a distinctive identity of the memory and data representing a distinctive identity of the cartridge. The cartridge has a data storage tape storing WORM data in a succession of data sets. Each data set is recorded with data representing a respectively associated data set information table. The data set information table includes an identifying data structure including data representing the identity of the cartridge memory and the data representing the identity of the cartridge. The integrity of all the WORM data written at any point along the tape can be checked against tampering by reference to the data structure that is recorded with each WORM data set.

Abstract: Locating a plurality of data records stored linearly on a data storage medium includes: reading data relating to the plurality of data records stored on the data storage medium from a memory device associated with the data storage medium; determining a position of the data record on the data storage medium for each data record to be read; and determining an order in which to read the plurality of data records from the data storage medium to minimize time needed to read the plurality of data records.

Abstract: Herein disclosed a method and apparatus for recovering user data from a data set comprising a plurality of sub data sets, wherein each data set contains a valid data length information, which is compared with an amount of valid user data collected from the data set prior to a sub data set in which an error occurred.

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 tape is associated with a semiconductor memory storing the end position of the last data of a data set recorded on the tape. The end location is stored in the memory before the last data are written to the tape. In a further operation mode, data identifying the location of one or plural successfully written data sets which have already been written to the tape are stored in the memory while user data are written to the tape.

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: Data are simultaneously written to plural tracks of a magnetic tape storage device while preventing elongated tape scratches from corrupting data blocks. A byte stream of user data is arranged into plural codewords that are distributed amongst plural heads that write the codewords to the plural tracks. When the data are read from the plural tracks, data are verified as being written to the tape successfully. If not, codewords are distributed amongst the plural read/write heads in a different order and re-written data to the tape.

Abstract: A data transfer device adapted to transfer data from a data storage medium having at least one data storage element the data transfer device comprising a head block having first and second transfer elements.

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: Recovery of user data from Partially incorrect data set in tape data storage system Herein disclosed a method and apparatus for recovering user data from a data set comprising a plurality of sub data sets, wherein each data set contains a valid data length information, which is compared with an amount of valid user data collected from the data set prior to a sub data set in which an error occurred.

Abstract: A method of encoding data to distinguish between new data and incompletely erased old data when restoring the data from a magnetic tape storage device comprises: arranging a byte stream of user data into a plurality of track blocks; adding to each track block a track block header containing a write pass identifier; as the data are written to tape, the write pass identifier of the data already on tape is read and the write pass identifier of the data being written to tape is incremented.

Abstract: A method of redundancy coding of user data received from a host apparatus and storage of said coded data on a magnetic tape data storage medium comprises inputting a byte stream of user data into a buffer and assembling a plurality of data sets in the buffer; for each data set assembling a data set into a two-dimensional data array and (1103) applying a second redundancy coding algorithm (C2 parity) to the two-dimensional data set in a second dimension; applying (1105) a first redundancy coding (C1 parity) algorithm to the second redundancy coded data array in a first dimension to form a two-dimensional data frame having second and first redundancy coding in respective second and first dimensions, the two-dimensional data frame comprising a plurality of rows, each row comprising a first codeword and a plurality of columns, each column comprising a second codeword; partitioning the two-dimensional data frame into a plurality of logical track blocks (1106) each comprising a plurality of first codewords; and rec