Efficient multichannel data format using variable-length headers

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 program instructions are executable by a tape drive to cause the tape drive to perform a method. The method includes writing data to a first write section of a magnetic tape, at least some of the data being written in association with first headers. The method also includes selecting some of the data for rewrite based on detected errors. Moreover, the method includes rewriting the selected data to a rewrite section of the magnetic tape, the rewritten data being written in association with rewrite headers. A length of each of the rewrite headers is greater than a length of each of the first headers.