Hewlett-packard Company

Other

Hewlett-packard Development Company, L.p.

Nigel Kevin Rushton

Mark Robert Watkins

Hideki Nonoyama

Robert Alan Williams

Tomonao Uchida

Shinya Ozaki

Stephen Morley

Simon Rae

A data storage device comprises a removable and replaceable magnetic tape cassette provided with a software control write protect switch. The switch is adapted to have a first condition in which data may be written to said magnetic tape and a second condition in which said switch is adapted to cause the blocking of a write operation to said tape. The switch is contained within a non-volatile electronic memory device and is electronically configurable between its first and second conditions remotely via a control signal.

Data storage device monitoring system, method and removable data carrier use with data storage systems

Data are detected and corrected with first and second error detecting and correcting stages. The first stage error detection and correction capabilities are determined by the number of errors it can detect and correct in a predetermined length data stream. The first stage determines the number of known and unknown data stream errors, corrects errors within its capability, and outputs to the second stage error states relative to the data stream. One state indicates no known data stream errors or first stage data stream correction being attained with less than first stage capability. Another state indicates the number of data stream errors exceeds the predetermined capability, resulting in failure to make the correction. A third state indicates correction of all data stream errors using all the first stage capability.

Error detection and correction

A sequence of data blocks written onto a medium of a data storage system includes first and subsequent appended data blocks having an append point code for identifying the first appended data block location. For data blocks having a running block number or frame number, the block or frame number of the first appended data block is stored as the append point code. The appended point code identifies the most recently append point location and aids in processes, such as tracking calibration, data integrity confirmation and track positioning.

Method of and apparatus for tracking appended data on storage medium

In a data storage system in which a sequence of data blocks is written onto a medium, appended data is distinguished by including in the first and subsequent appended data blocks an append point code uniquely identifying the location of the first appended data block. Where the data blocks have a running block number or frame number, the block or frame number of the first appended data block is stored as the append point code. This clearly identifies the most recent append point location which will aid in processes such as tracking calibration data integrity confirmation and track positioning.

A method for correcting errors when writing a stream of data to a data, received from a host apparatus, to a magnetic tape data storage medium comprises: partitioning the stream of digital data into a plurality of fragments; writing the plurality of fragments to the data storage medium; reading the plurality of fragments from the data storage medium; checking whether each of the read fragments are correct; assigning each of the correct read fragments to only one of a plurality of groups of fragments; counting a total number of correct read fragments within each of the plurality of groups of fragments; and if the total number of correct read fragments within any of the plurality of groups of fragments is less than the threshold number of correct read fragments then the step of writing the plurality of fragments to the data storage medium is repeated.

Data writing to data storage medium

Data are stored on magnetic tape along successive tracks extending obliquely across the tape, in each of several areas including a lead-in area, a data area and an end-of-data (EOD) area. Each track comprises successive blocks or fragments of data, and each fragment has a compact header containing a synchronization byte, six information bytes and two parity bytes. The information bytes include a fragment ID, an area ID sub code identifying the area in which the fragment is located, and various other sub codes relating to logical structure of the data. The inclusion of an area ID sub code and logical structure sub codes in the (compact) header of every fragment facilitates reliable searching of the data stored on the tape at high tape advance speeds.

Methods and apparatus for storing data and auxiliary information

A data storage device for reading and/or writing data to a storage medium includes a buffer memory (15) for smoothing the flow of data to/from the storage medium. Activation of the storage apparatus (9) to read/write data from/to the storage medium is generally controlled in dependence upon the amount of data held in the buffer (13). In order to optimize utilization of the buffer (15), it is proposed to adaptively set the threshold level at which such activation is effected. To this end, the utilization of the buffer (13) during a previous activation is monitored and a new threshold value is set in dependence on the monitored utilization parameter.

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Bristol, United Kingdom

Nigel Kevin Rushton