Patent ID: 7143318

Claim:
A method for identifying systematic errors in a data recording device, comprising: writing a plurality of data sets to a recording medium, each data set comprising a plurality of data segments; identifying erroneously written data segments of each data set; for each data set, storing in a buffer cell a value representative of the number of erroneously written data segments for the data set; determining the number PR 1A of a first plurality L of buffer cells which contain stored values in excess of a first predetermined threshold value TH HB-1A ; determining the number PR 2A of a second plurality M of buffer cells which contain stored values in excess of a second predetermined threshold value TH HB-2A , where M<L; and generating an output signal indicating at least one of: whether the number PR 1A exceeds a third predetermined threshold value TH PR-1A and whether the number PR 2A exceeds a fourth predetermined threshold value TH PR-2A .