A method is provided, which includes reading data from a data storage
medium. Reading data from the medium causes the data to be erased. The
method further includes determining a desired position to rewrite the
data by computing a position error signal based on the data signal and
compensating the position error signal for non-zero bias. The data is
then rewritten non-synchronously. An apparatus is also provided,
including a data storage medium with a data communication transducer
configured to receive data from the medium. Data is erased after it is
read. The data communication transducer is configured to rewrite the read
data back onto the data storage medium in a non-synchronously. A non-zero
bias compensator is provided to compensate data received by the data
communication transducer to determine a desired position to rewrite the
previously read data back onto the medium.