Efficient rewrite using larger codeword sizes

A method, comprising:

• writing, using a plurality of at least M write transducers of a magnetic head, a data set to a sequential access medium, the data set comprising a number of sub data sets of fixed size, each sub data set comprising a plurality of encoded data blocks comprising codewords in an interleaved or non-interleaved arrangement, each codeword comprising a predetermined number of symbols having a size of at least 8 bits for each symbol;
• reading, using a plurality of at least M read transducers of the magnetic head, the data set immediately after being written to the sequential access medium in a read-while-write process to identify one or more faulty encoded data blocks, each of the one or more faulty encoded data blocks comprising at least one faulty codeword;
• selecting a particular logical track from a predetermined subset of logical tracks in a rewrite area of the sequential access medium to rewrite the faulty encoded data blocks, the rewrite area being positioned subsequent to a position of the data set first written on the sequential access medium, wherein the predetermined subset of logical tracks includes D1+D2+1 logical tracks, and wherein 0<D1+D2<M/4;
• and
• rewriting a first of the one or more faulty encoded data blocks within a first encoded data block set to the particular logical track in the rewrite area of the sequential access medium, wherein only one faulty encoded data block from a particular sub data set is rewritten in a single encoded data block set in the rewrite area.

A computer program product, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the embodied program instructions being executable by a processor to cause the processor to:

• write, by the processor using a plurality of at least M write transducers of a magnetic head, a data set to a sequential access medium, the data set comprising a number of sub data sets of fixed size, each sub data set comprising a plurality of encoded data blocks comprising codewords in an interleaved or non-interleaved arrangement, each codeword comprising a predetermined number of symbols having a size of at least 8 bits for each symbol;
• read, by the processor using a plurality of at least M read transducers of the magnetic head, the data set immediately after being written to the sequential access medium in a read-while-write process to identify one or more faulty encoded data blocks, each of the one or more faulty encoded data blocks comprising at least one faulty codeword;
• select, by the processor, a particular logical track from a predetermined subset of logical tracks in a rewrite area of the sequential access medium to rewrite the faulty encoded data blocks, the rewrite area being positioned subsequent to a position of the data set first written on the sequential access medium, wherein the predetermined subset of logical tracks includes D1+D2+1 logical tracks, and wherein 0<D1+D2<M/4;
• and
• rewrite, by the processor, a first of the one or more faulty encoded data blocks within a first encoded data block set to the particular logical track in the rewrite area of the sequential access medium, wherein only one faulty encoded data block from a particular sub data set is rewritten in a single encoded data block set in the rewrite area.

A method, comprising:

• writing, using a plurality of write transducers of a magnetic head, a data set to a sequential access medium, the data set comprising a number of sub data sets of fixed size, each sub data set comprising a plurality of encoded data blocks comprising codewords in an interleaved arrangement, each codeword comprising a predetermined number of symbols;
• reading, using a plurality of read transducers of the magnetic head, the data set immediately after being written to the sequential access medium in a read-while-write process to identify one or more faulty encoded data blocks, each of the one or more faulty encoded data blocks comprising at least one faulty codeword;
• decoding the data set read from the sequential access medium to determine the one or more faulty encoded data blocks, wherein an encoded data block is determined to be faulty in response to detection of a threshold number of errors therein after the encoded data block is decoded;
• selecting one or more logical tracks from one or more unique predetermined subsets of logical tracks in a rewrite area of the sequential access medium to rewrite the one or more faulty encoded data blocks, the rewrite area being positioned subsequent to a position of the data set first written on the sequential access medium, wherein each of the predetermined subsets of logical tracks includes three logical tracks;
• and
• rewriting the one or more faulty encoded data blocks within one or more encoded data block sets to the one or more logical tracks in the rewrite area of the sequential access medium, wherein only one faulty encoded data block from a particular sub data set is rewritten in a single encoded data block set in the rewrite area,
• wherein each encoded data block is written to the sequential access medium as two symbol-interleaved Reed-Solomon RS(384,364) C1 codewords over a Galois Field GF(1024).

A method, comprising:

• writing, using a plurality of write transducers of a magnetic head, a data set to a sequential access medium, the data set comprising a number of sub data sets of fixed size, each sub data set comprising a plurality of encoded data blocks comprising codewords, each codeword comprising a predetermined number of symbols;
• reading, using a plurality of read transducers of the magnetic head, the data set immediately after being written to the sequential access medium in a read-while-write process to identify one or more faulty encoded data blocks, each of the one or more faulty encoded data blocks comprising at least one faulty codeword;
• decoding the data set read from the sequential access medium to determine the one or more faulty encoded data blocks, wherein an encoded data block is determined to be faulty in response to detection of a threshold number of errors therein after the encoded data block is decoded;
• selecting one or more logical tracks from one or more unique predetermined subsets of logical tracks in a rewrite area of the sequential access medium to rewrite the one or more faulty encoded data blocks, the rewrite area being positioned subsequent to a position of the data set first written on the sequential access medium, wherein each of the predetermined subsets of logical tracks includes five logical tracks;
• and
• rewriting the one or more faulty encoded data blocks within one or more encoded data block sets to the one or more logical tracks in the rewrite area of the sequential access medium, wherein only one faulty encoded data block from a particular sub data set is rewritten in a single encoded data block set in the rewrite area,
• wherein each encoded data block is written to the sequential access medium as one Reed-Solomon RS(768,728) C1 codeword over a Galois Field GF(1024).