Disk drive generating quality metric map for a data track while in different configurations

1. A disk drive comprising:

a disk comprising a plurality of servo tracks defined by servo sectors;

a head actuated over the disk; and

control circuitry comprising a read channel, the control circuitry operable to:

define a plurality of data tracks relative to the servo tracks, wherein each data track comprises at least one data segment between consecutive servo sectors;

configure the read channel into a read mode in order to first read a first data segment of a first data track;

during the first read, generate a quality metric at periodic points along the first data segment;

after the first read, configure the read channel into a non-read mode for a predetermined interval;

after the predetermined interval, configure the read channel into the read mode in order to second read the first data segment of the first data track; and

during the second read, generate the quality metric at the periodic points along the first data segment,

wherein during the predetermined interval the control circuitry is further operable to seek the head away from the first data track by at least one data track and then seek the head back to the first data track.

2. The disk drive as recited in claim 1 , wherein after seeking the head back to the first data track and prior to second reading the first data segment the control circuitry is further operable to first read a second data segment from the first data track and generate the quality metric at periodic points along the second data segment.

3. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to alternate between seeking away from the first data track and back to the first data track in order to read additional data segments and generate a quality metric at periodic points along the additional data segments.

4. The disk drive as recited in claim 1 , wherein each point along the first data segment corresponds to a data sector of the first data track.

5. The disk drive as recited in claim 4 , wherein the quality metric comprises a flag indicating when the data sector is recoverable.

6. The disk drive as recited in claim 4 , wherein the quality metric comprises a number of errors detected in a data sector.

7. The disk drive as recited in claim 4 , wherein the control circuitry comprises an iterative data detector operable to detect each data sector over one or more iterations, and the quality metric comprises a number of iterations needed to recover a data sector.

8. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to:

when second seeking the head away from the first data track, seek the head to a second data segment of a second data track; and

read the second data segment and generate the quality metric at periodic points along the second data segment.

9. A disk drive comprising:

a disk comprising a plurality of servo tracks defined by servo sectors;

a head actuated over the disk; and

control circuitry comprising write circuitry and a read channel, the control circuitry operable to:

define a plurality of data tracks relative to the servo tracks, wherein each data track comprises at least one data segment between consecutive servo sectors;

first seek the head to a first data track comprising a first data segment followed by a second data segment;

when the head reaches the second data segment during a first revolution of the disk, enable the write circuitry and write data to the second data segment;

during a second revolution of the disk, read the first data segment in order to initialize the read channel and after reading the first data segment, read the second data segment and generate a quality metric at periodic points along the second data segment;

second seek the head away from the first data track;

third seek the head to a third data segment of the first data track and write data to the third data segment;

read the data from the second and third data segments and generate a quality metric at periodic points along the second and third data segments; and

save each quality metric and a corresponding location within the first data track.

10. The disk drive as recited in claim 9 , wherein the control circuitry is further operable to:

when second seeking the head away from the first data track, seek the head to a fourth data segment of a second data track and write data to the fourth data segment;

after writing the data to the third data segment of the first data track, seek the head to a fifth data segment of the second data track and write data to the fifth data segment; and

read the data from the fourth and fifth data segments and generate the quality metric at periodic points along the fourth and fifth data segments.

11. A method of operating a disk drive, the method comprising:

defining a plurality of data tracks relative to a plurality of servo tracks of a disk, wherein each data track comprises at least one data segment between consecutive servo sectors;

configuring a read channel into a read mode in order to first read a first data segment of a first data track;

during the first read, generating a quality metric at periodic points along the first data segment;

after the first read, configuring the read channel into a non-read mode for a predetermined interval;

after the predetermined interval, configuring the read channel into the read mode in order to second read the first data segment of the first data track; and

during the second read, generating the quality metric at the periodic points along the first data segment,

wherein during the predetermined interval the method further comprises seeking a head actuated over the disk away from the first data track by at least one data track and then seeking the head back to the first data track.

12. The method as recited in claim 11 , wherein after seeking the head back to the first data track and prior to second reading the first data segment the method further comprises first reading a second data segment from the first data track and generating the quality metric at periodic points along the second data segment.

13. The method as recited in claim 11 , further comprising alternating between seeking away from the first data track and back to the first data track in order to read additional data segments and generate a quality metric at periodic points along the additional data segments.

14. The method as recited in claim 11 , wherein each point along the first data segment corresponds to a data sector of the first data track.

15. The method as recited in claim 14 , wherein the quality metric comprises a flag indicating when the data sector is recoverable.

16. The method as recited in claim 14 , wherein the quality metric comprises a number of errors detected in a data sector.

17. The method as recited in claim 14 , wherein control circuitry of the disk drive comprises an iterative data detector operable to detect each data sector over one or more iterations, and the quality metric comprises a number of iterations needed to recover a data sector.

18. The method as recited in claim 11 , further comprising:

when second seeking the head away from the first data track, seeking the head to a second data segment of a second data track; and

reading the second data segment and generating the quality metric at periodic points along the second data segment.

19. A method of operating a disk drive, the method comprising:

defining a plurality of data tracks relative to a plurality of servo tracks of a disk, wherein each data track comprises at least one data segment between consecutive servo sectors;

first seeking a head to a first data track comprising a first data segment followed by a second data segment;

when the head reaches the second data segment during a first revolution of the disk, enabling write circuitry and writing data to the second data segment;

during a second revolution of the disk, reading the first data segment in order to initialize a read channel and after reading the first data segment, reading the second data segment and generate a quality metric at periodic points along the second data segment;

second seeking the head away from the first data track;

third seeking the head to a third data segment of the first data track and writing data to the third data segment;

reading the data from the second and third data segments and generating a quality metric at periodic points along the second and third data segments; and

saving each quality metric and a corresponding location within the first data track.

20. The method as recited in claim 19 , further comprising:

when second seeking the head away from the first data track, seeking the head to a fourth data segment of a second data track and writing data to the fourth data segment;

after writing the data to the third data segment of the first data track, seeking the head to a fifth data segment of the second data track and writing data to the fifth data segment; and

reading the data from the fourth and fifth data segments and generating the quality metric at periodic points along the fourth and fifth data segments.

21. A disk drive comprising:

a disk comprising a plurality of servo tracks defined by servo sectors;

a head actuated over the disk; and

control circuitry comprising a read channel, the control circuitry operable to:

define a plurality of data tracks relative to the servo tracks, wherein each data track comprises at least one data segment between consecutive servo sectors;

configure the read channel into a read mode in order to first read a first data segment of a first data track;

during the first read, generate a quality metric at periodic points along the first data segment;

after the first read, configure the read channel into a non-read mode for a predetermined interval;

after the predetermined interval, configure the read channel into the read mode in order to second read the first data segment of the first data track;

during the second read, generate the quality metric at the periodic points along the first data segment; and

accumulate the quality metrics generated at each point during the first and second read.

22. A method of operating a disk drive, the method comprising:

defining a plurality of data tracks relative to a plurality of servo tracks of a disk, wherein each data track comprises at least one data segment between consecutive servo sectors;

configuring a read channel into a read mode in order to first read a first data segment of a first data track;

during the first read, generating a quality metric at periodic points along the first data segment;

after the first read, configuring the read channel into a non-read mode for a predetermined interval;

after the predetermined interval, configuring the read channel into the read mode in order to second read the first data segment of the first data track;

during the second read, generating the quality metric at the periodic points along the first data segment; and

accumulating the quality metrics generated at each point during the first and second read.