Abstract: A method and associated system for monitoring errors that occur in magnetic media storage read and write operations, for identifying uncorrectable errors and classifying them. In the system, a counter keeps track of specific locations of data blocks as well as the physical locations of the data recorded upon the media. When an error occurs in read or write operations that cannot be corrected by the error correction circuits, the error location is stored. After an error correction procedure, including usual retry operations, is completed, the count values of the error correction procedures are also stored. Means are provided for comparing the recorded error counts for initial and retry operations. A match of error positions, not correctable through standard error recovery procedures and in the presence of valid recording channel electronics operation, indicates a media defect at the identified location.