Browse Prior Art Database

In-Situ Disk Durability Monitoring Disclosure Number: IPCOM000117833D
Original Publication Date: 1996-Jun-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 34K

Publishing Venue


Related People

Kimball, SW: AUTHOR [+2]


Disclosed is a method for detecting and counting thermal asperities in a disk drive.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

In-Situ Disk Durability Monitoring

      Disclosed is a method for detecting and counting thermal
asperities in a disk drive.

      Thermal asperity signals that occur in the landing zone of a
disk drive indicate that a head is not taking off and thus will fail

      Heads which have low flying height, and a high take-off speed,
are prone to generating Thermal Asperities (TAs).  Thermal asperity
signals are also possible due to contact with debris in the landing
zone.  Given the extreme sensitivity of the Magnetoresistive (MR)
head to debris contact and the difficulty of controlling all
contamination, excessive TAs in the landing zone are indicative of a
pending stop/start failure.

      An in-situ check for thermal asperities can be made as a
Predictive Failure Analysis (PFA) feature.  For PFA, the presence of
TAs in the landing zone can be determined a number of ways.  For
example, by erasing any previously written data in the landing zone,
signals from the TAs can be detected using the channel electronics.
The Automatic Gain Control (AGC) gain is held and the readback signal
sampled to determine if voltage spikes caused by TAs are present.
The TA count per revolution could be used for a threshold.  The check
could be made just after spin-up or just before spin-down.  To
establish a margin, the drive RPM could be reduced in the landing
zone to determine how much the spindle has to be slowed to generate