System and method for processing track identifier errors to mitigate head instability in data storage devices
View Patent ↗A system and method for processing track identifier errors to mitigate head instability in data storage devices is disclosed. The system and method includes computing a track id differential between an expected track id and a received track id, encoding the expected track id and the received track id, initiating a first action if the track id differential exceeds a pre-determined threshold and the encoded expected track id varies from the encoded received track id by a pre-configured number of bits, and initiating a second action if the track id differential does not exceed the pre-determined threshold or the encoded expected track id does not vary from the encoded received track id by a pre-configured number of bits.
1. A method, comprising:
reading a received track id from a disk;
computing a track id differential between the received track id and an expected track id;
Gray encoding the received track id and the expected track id, wherein the Gray-encoded received track id and the Gray-encoded expected track id each comprise a plurality of bits;
detecting any mismatch between the bits of the Gray-encoded received track id and the bits of the Gray-encoded expected track id;
initiating a first action if the track id differential exceeds a pre-determined threshold and the mismatch between the bits of the Gray-encoded received track id and the bits of the Gray-encoded expected track id is of a pre-configured number of bits; and
initiating a second action if the track id differential exceeds a pre-determined threshold and the mismatch between the bits of the Gray-encoded received track id and the bits of the Gray-encoded expected track id is not of a pre-configured number of bits.
2. The method of claim 1 , wherein the first action includes recording an error using a first penalty value.
3. The method of claim 2 wherein the second action includes recording an error using a second penalty value.
4. The method of claim 1 wherein the first action includes correcting the received track id.
5. The method of claim 1 , wherein the second action includes performing an error recovery operation.
6. The method of claim 1 , wherein detecting any mismatch between the bits of the Gray-encoded received track id and the bits of the Gray-encoded expected track id comprises computing a Hamming distance between the Gray-encoded received track id and the Gray-encoded expected track id.
7. The method of claim 1 , wherein the pre-configured number of bits is one bit.
8. The method of claim 1 , wherein the pre-configured number of bits is two bits.
9. A disk drive, comprising:
a track id detector operable to read a received track id from a disk;
a track id differential generator operable to determine a track id differential between the received track id and an expected track id;
a track id encoder operable to Gray-encode the received track id and the expected track id, wherein the Gray-encoded received track id and the Gray-encoded expected track id each comprise a plurality of bits;
an N-bit mismatch detector operable to detect any mismatch between the bits of the Gray-encoded received track id and the bits of the Gray-encoded expected track id;
a first action initiator operable to initiate a first action if the track id differential exceeds a pre-determined threshold and the mismatch between the bits of the Gray-encoded received track id and the bits of the Gray-encoded expected track id is of a pre-configured number of bits; and
a second action initiator operable to initiate a second action if the track id differential exceeds a pre-determined threshold and the mismatch between the bits of the Gray-encoded received track id and the bits of the Gray-encoded expected track id is not of a pre-configured number of bits.
10. The method of claim 9 , wherein the first action includes recording an error using a first penalty value.
11. The method of claim 10 wherein the second action includes recording an error using a second penalty value.
12. The method of claim 9 wherein the first action includes correcting the received track id.
13. The method of claim 9 , wherein the second action includes performing an error recovery operation.
14. The method of claim 9 , wherein the N-bit mismatch detector is further operable to compute a Hamming distance between the Gray-encoded received track id and the Gray-encoded expected track id.
15. The method of claim 9 , wherein the pre-configured number of bits is one bit.
16. The method of claim 9 , wherein the pre-configured number of bits is two bits.