Abstract: A method and apparatus for monitoring the quality of the readback signal of data written on a magnetic recording disk in a disk drive and for limiting data loss due to physical damage at a slider/disk interface. The amplitude of a read signal is continuously monitored in the read channel, either by directly measuring the read signal amplitude or by monitoring the amplification level of the automatic gain control (AGC) circuit in the read channel which is inversely proportional to the read signal amplitude. If the amplitude of the monitored read signal decreases below a chosen level, the location of the data on the disk track is flagged as possibly damaged. The data is rewritten at the same location and then reread to see if full recovery of the degraded data is possible. If the amplitude read signal of the rewritten data is greater than a chosen level, the disk track is judged to be usable and normal operation continues.

Abstract: A method for increasing boot speed of a host computer with associated hard disk drive generates a prefetch table that contains pointers to disk locations and lengths of the records of an application program requested by the host computer during an initial power-on/reset. During the next power-on/reset, before the host computer is ready for data but after the disk drive has completed its reset routine, using the prefetch table the disk drive accesses the previously requested data and copies it onto the cache of the disk drive, from where it is transferred to the host computer when the host computer requests it. The prefetch table is updated to reflect disk location changes for the various records, or to reflect new records that were requested by the host computer but not found in cache during the previous power-on/reset.