Patent ID: 6958873

Claim:
Apparatus for transferring data from a host computing system to one or more magnetic tape storage devices or the like, the apparatus comprising: an input apparatus for receiving data, dividing it into blocks, and converting said blocks of data to a format suitable for storage on said one or more storage devices; one or more data writers for writing said blocks of data in sets of a plurality of blocks to said one or more storage devices, data being adapted to be written to the one or more storage devices in codeword quad (CQ) sets comprising an array of ECC encoded codeword pairs; one or more data readers for reading back data written to said one or more storage devices and transferring said read data to error checking apparatus, said error checking apparatus being arranged to generate a negative output only if a block of data includes an error and/or more than a predetermined number of errors; a control apparatus for causing said one or more data writers to rewrite a set of blocks of data to said one or more storage devices in response to a negative output from said error checking apparatus, until all of the blocks of data in that set are written without error (or with fewer than a predetermined number of errors) during the same rewrite; and a history store for storing information relating to at least some of the CQ sets written to the one or more storage devices, together with information corresponding to the output of the error checking apparatus for each codeword pair of the set.