Scratch protection in tape data storage system

An encoding apparatus for encoding a byte stream of data, said encoding apparatus comprising:

• a data processor for arranging said byte stream into a two-dimensional data array;
• an encoder arrangement for encoding said two-dimensional data array with (a) a first redundancy coding in a first of said dimensions and (b) a second redundancy coding in a second of said dimensions;
• said encoder arrangement being arranged for:
• (a) forming a plurality of track blocks having the first and second redundancy coding distributed over said plurality of track blocks within said two-dimensional data array, each of said track blocks comprising a plurality of first codeword pairs, (b) writing each track block along a single corresponding physical track of the tape, and (c) distributing bytes of each of second codewords of said data array over said plurality of track blocks to cause the distributed bytes of said second codewords to extend over said plurality of physical track blocks on the tape.

A tape storing plural track blocks in a data frame resulting from a byte stream of data being arranged into a data set, each track block comprising plural complete first codeword pairs, and redundancy coding of the data set;

• the redundancy coding of said data frame being distributed over said track blocks within the data frame;
• the tape comprising plural elongated side-by-side physical tracks over which said data frame is distributed, the tracks being parallel to each other and to elongated edges of the tape;
• said data frame being distributed on the tape so it includes plural first codewords arranged in a first dimension in the tracks and plural second codewords arranged in a second dimension;
• each track block comprising plural complete first codeword pairs;
• each track block being located in a single track on the tape;
• and
• bytes of each second codeword of said data frame being distributed over said plural track blocks such that said bytes of the second codewords extend over said plural side-by-side tracks.