an apparatus and method are provided for tracking the number of permanent and temporary errors , and spare sectors used as a result of the errors , on a per disk and per drive basis . during read / write operations , a determination is made as to whether the number of spares used to replace defective sectors on a disk , together with the number of spares used to replace defective sectors during formatting , exceeds a predetermined limit . this limit can be different depending upon the type of disk in use , rewritable or worm . if the limit is exceeded , diagnostics are executed to ascertain the cause of the excess usage and appropriate corrective action , such as requesting that the disk and drive lens be cleaned , is initiated . moreovers , an attempt can be made to recover used spare sectors on a rewritable disk .