Abstract: DASD failures occurring on sector boundaries currently go undetected. While this sort of problem can occur at any time, it usually occurs when the program executing on the computer system's processor is operating on a multisector piece of data and periodically updating that information in auxiliary storage so that the copy in auxiliary storage is relatively up to date with the changes being made by the program. The storage management mechanism of the present invention solves the problem of sector boundary write failures by associating a sequence number with each piece of multisector data. Essentially, the sequence number becomes a property of the particular piece of data itself. When the mechanism retrieves the information from disk, it checks to make sure that all the sequence numbers match. If they do not, a data integrity problem has been detected.