Systems and methods for logically organizing data for storage and recovery on a data storage medium using a multi-level format are described. Embodiments include systems and methods for protecting data stored on a data storage medium so that the data may be recovered without errors.

A soft input decoding method and a decoder for generalized concatenated (GC) codes. The GC codes are constructed from inner nested block codes, such as binary Bose-Chaudhuri-Hocquenghem, BCH, codes and outer codes, such as Reed-Solomon, RS, codes. In order to enable soft input decoding for the inner block codes, a sequential stack decoding algorithm is used. Ordinary stack decoding of binary block codes requires the complete trellis of the code. In one aspect, the present invention applies instead a representation of the block codes based on the trellises of supercodes in order to reduce the memory requirements for the representation of the inner codes. This enables an efficient hardware implementation. In another aspect, there is provided a soft input decoding method and device employing a sequential stack decoding algorithm in combination with list-of-two decoding which is particularly well suited for applications that require very low residual error rates.

A magazine-based data storage library in connection with a disk drive-based archive storage system is described that essentially generates parity data for tape formatted data streams (stored to tape cartridges) that do not align by way of data blocks or file marks. Data streams intended for tape storage sent to tape cartridges are also sent to a disk drive storage system via an encoder where parity of the data streams can be generated. More specifically, the encoder digitally formats tape blocks and tape marks (as well as other tape formatted structure) in a digital stream of data that can be added to other encoded digital streams of data to generate parity. To reconstruct a specific tape cartridge from a tape set, the encoded data from each of the tapes in the tape set are subtracted from the parity data and the remaining encoded data is decoded and sent to a designated tape cartridge.

In one embodiment, a system includes a processor, and logic integrated with the processor, executable by the processor, or integrated with and executable by the processor. The logic is configured to cause the processor to write, by the processor, data to a storage medium of a data storage system using a partial reverse concatenated modulation code. The partial reverse concatenated modulation code comprises encoding the data by applying a C2 encoding scheme prior to encoding the data by applying one or more modulation encoding schemes, followed by encoding the data by applying a C1 encoding scheme subsequent to the encoding of the data with the one or more modulation encoding schemes.

The invention relates to a soft input decoding method and a decoder for generalized concatenated (GC) codes. The GC codes are constructed from inner nested block codes, such as binary Bose-Chaudhuri-Hocquenghem, BCH, codes and outer codes, such as Reed-Solomon, RS, codes. In order to enable soft input decoding for the inner block codes, a sequential stack decoding algorithm is used. Ordinary stack decoding of binary block codes requires the complete trellis of the code. In one aspect, the present invention applies instead a representation of the block codes based on the trellises of supercodes in order to reduce the memory requirements for the representation of the inner codes. This enables an efficient hardware implementation. In another aspect, the present invention provides a soft input decoding method and device employing a sequential stack decoding algorithm in combination with list-of-two decoding which is particularly well suited for applications that require very low residual error rates.

In one embodiment, a computer program product includes a computer readable storage medium having program instructions embodied therewith. The computer readable storage medium is not a transitory signal per se. The embodied program instructions are readable/executable by a processor to cause the processor to write, by the processor, data to a storage medium of a data storage system using a partial reverse concatenated modulation code. The partial reverse concatenated modulation code includes encoding the data by applying a C2 encoding scheme prior to encoding the data by applying one or more modulation encoding schemes, followed by encoding the data by applying a C1 encoding scheme subsequent to the encoding of the data with the one or more modulation encoding schemes. Other computer program products for writing data to a storage medium of a data storage system using a partial reverse concatenated modulation code are presented according to more embodiments.

In one embodiment, a system includes a processor, and logic integrated with the processor, executable by the processor, or integrated with and executable by the processor. The logic is configured to cause the processor to write, by the processor, data to a storage medium of a data storage system using a partial reverse concatenated modulation code. The partial reverse concatenated modulation code comprises encoding the data by applying a C2 encoding scheme prior to encoding the data by applying one or more modulation encoding schemes, followed by encoding the data by applying a C1 encoding scheme subsequent to the encoding of the data with the one or more modulation encoding schemes.

A magazine-based data storage library in connection with a disk drive-based archive storage system is described that essentially generates parity data for tape formatted data streams (stored to tape cartridges) that do not align by way of data blocks or file marks. Data streams intended for tape storage sent to tape cartridges are also sent to a disk drive storage system via an encoder where parity of the data streams can be generated. More specifically, the encoder digitally formats tape blocks and tape marks (as well as other tape formatted structure) in a digital stream of data that can be added to other encoded digital streams of data to generate parity. To reconstruct a specific tape cartridge from a tape set, the encoded data from each of the tapes in the tape set are subtracted from the parity data and the remaining encoded data is decoded and sent to a designated tape cartridge.

A magazine-based data storage library in connection with a disk drive-based archive storage system is described that essentially generates parity data for tape formatted data streams (stored to tape cartridges) that do not align by way of data blocks or file marks. Data streams intended for tape storage sent to tape cartridges are also sent to a disk drive storage system via an encoder where parity of the data streams can be generated. More specifically, the encoder digitally formats tape blocks and tape marks (as well as other tape formatted structure) in a digital stream of data that can be added to other encoded digital streams of data to generate parity. To reconstruct a specific tape cartridge from a tape set, the encoded data from each of the tapes in the tape set are subtracted from the parity data and the remaining encoded data is decoded and sent to a designated tape cartridge.

Mechanisms are provided to receive encoded header information stored on a tape of a tape drive, wherein the encoded header information has been generated by: generating, for a plurality of tracks of the tape of the tape drive, a header information in a plurality of symbols, wherein the plurality of symbols is comprised of a first set of symbols and a second set of symbols, wherein the first set of symbols include identical information across all tracks of the plurality of tracks, and wherein the second set of symbols are configurable to include different information across all tracks of the plurality of tracks; and modifying, for writing to the tape of the tape drive, the first set of symbols of the plurality of tracks to include parity information corresponding to information included in the second set of symbols of the plurality of tracks. The received encoded header information is decoded.