Magnetic disk device and method
According to one embodiment, a first storage area and a second storage area in which a plurality of tracks are set are provided in a radial direction of a magnetic disk. A plurality of post codes corresponding to the second storage area is stored in the first storage area. A controller controls first processing of reading a plurality of post codes from the first storage area and writing the plurality of read post codes in servo area of the second storage area. In the first processing, the controller controls both second processing and third processing in a state where a write head is located on a first track. The second processing is processing of writing a post code among the plurality of read post codes in a servo area. The third processing is processing of writing user data in a data area or reading user data from a data area.
1. A magnetic disk device comprising:
a magnetic disk in which a first storage area and a second storage area in which a plurality of tracks are set are provided in a radial direction, a plurality of post codes for correcting positional displacement of the plurality of tracks being stored in the first storage area, a third storage area and a fourth storage area being provided in a circumferential direction in the second storage area;
a magnetic head including a write head that executes writing to the magnetic disk and a read head that executes reading from the magnetic disk; and
a controller that executes control of executing first processing of reading the plurality of post codes from the first storage area and writing the plurality of read post codes in the third storage area of the second storage area, and executes, in the first processing, in a state where the write head is located on a first track among the plurality of tracks, control of executing both second processing of writing a first post code among the plurality of read post codes in the third storage area and third processing of writing user data in the fourth storage area or reading user data from the fourth storage area.
2. The magnetic disk device according to claim 1 , wherein the first post code is a post code for correcting positional displacement of a second track, and
the second track is a track at which the write head is located in a state where the read head is located on the first track.
3. The magnetic disk device according to claim 2 ,
wherein the controller executes control of:
in the first processing, acquiring an amount of positional displacement of a third track adjacent to the second track among the plurality of tracks and correcting the first post code on a basis of the amount of the positional displacement of the third track; and
in the second processing, writing of the corrected first post code.
4. The magnetic disk device according to claim 3 ,
wherein the controller
generates a second post code for correcting the positional displacement of the third track on a basis of the acquired amount of the positional displacement of the third track, and
corrects the first post code through weighted addition of the first post code and the generated second post code.
5. The magnetic disk device according to claim 1 , wherein the controller is configured to arrange the plurality of tracks in accordance with a first scheme, and be capable of switching the first scheme between two second schemes,
the plurality of post codes includes two sets of post codes, each of the two sets corresponding to a respective second scheme among the two second schemes, and
the controller, in the first processing, executes control of reading a set which corresponds to a second scheme to which the first scheme is switched among the two sets from the first storage area and writing post codes included in the read set in the third storage area of the second storage area.
6. The magnetic disk device according to claim 2 ,
wherein the controller is configured to arrange the plurality of tracks in accordance with a first scheme, and be capable of switching the first scheme between two second schemes,
the plurality of post codes includes two sets of post codes, each of the two sets corresponding to a respective second scheme among the two second schemes, and
the controller, in the first processing, executes control of reading a set which corresponds to a second scheme to which the first scheme is switched among the two sets from the first storage area and writing post codes included in the read set in the third storage area of the second storage area.
7. The magnetic disk device according to claim 3 ,
wherein the controller is configured to arrange the plurality of tracks in accordance with a first scheme, and be capable of switching the first scheme between two second schemes,
the plurality of post codes includes two sets of post codes, each of the two sets corresponding to a respective second scheme among the two second schemes, and
the controller, in the first processing, executes control of reading a set which corresponds to a second scheme to which the first scheme is switched among the two sets from the first storage area and writing post codes included in the read set in the third storage area of the second storage area.
8. The magnetic disk device according to claim 4 ,
wherein the controller is configured to arrange the plurality of tracks in accordance with a first scheme, and be capable of switching the first scheme between two second schemes,
the plurality of post codes includes two sets of post codes, each of the two sets corresponding to a respective second scheme among the two second schemes, and
the controller, in the first processing, executes control of reading a set which corresponds to a second scheme to which the first scheme is switched among the two sets from the first storage area and writing post codes included in the read set in the third storage area of the second storage area.
9. The magnetic disk device according to claim 5 ,
wherein one of the two second schemes is a scheme in which the plurality of tracks is arranged so that data is written in a manner such that data of one track between two tracks which are adjacent to each other in a radial direction of the magnetic disk overlaps with part of data of the other track between the two tracks, and
the other of the two second schemes is a scheme in which the plurality of tracks is arranged so that data of two tracks which are adjacent to each other in the radial direction of the magnetic disk do not overlap with each other.
10. The magnetic disk device according to claim 6 ,
wherein one of the two second schemes is a scheme in which the plurality of tracks is arranged so that data is written in a manner such that data of one track between two tracks which are adjacent to each other in a radial direction of the magnetic disk overlaps with part of data of the other track between the two tracks, and
the other of the two second schemes is a scheme in which the plurality of tracks is arranged so that data of two tracks which are adjacent to each other in the radial direction of the magnetic disk do not overlap with each other.
11. The magnetic disk device according to claim 7 ,
wherein one of the two second schemes is a scheme in which the plurality of tracks is arranged so that data is written in a manner such that data of one track between two tracks which are adjacent to each other in a radial direction of the magnetic disk overlaps with part of data of the other track between the two tracks, and
the other of the two second schemes is a scheme in which the plurality of tracks is arranged so that data of two tracks which are adjacent to each other in the radial direction of the magnetic disk do not overlap with each other.
12. The magnetic disk device according to claim 8 ,
wherein one of the two second schemes is a scheme in which the plurality of tracks is arranged so that data is written in a manner such that data of one track between two tracks which are adjacent to each other in a radial direction of the magnetic disk overlaps with part of data of the other track between the two tracks, and
the other of the two second schemes is a scheme in which the plurality of tracks is arranged so that data of two tracks which are adjacent to each other in the radial direction of the magnetic disk do not overlap with each other.
13. A magnetic disk device comprising:
a magnetic disk including a first storage area in which a plurality of tracks is arranged in a radial direction, a second storage area and a third storage area being provided in a circumferential direction in the first storage area, a plurality of post codes for correcting positional displacement of the plurality of tracks being stored in the second storage area;
a magnetic head including a write head that executes writing to the magnetic disk and a read head that executes reading from the magnetic disk; and
a controller that executes, in a first state in which the magnetic head is positioned, control of executing access to the third storage area on a track among the plurality of tracks in accordance with a write command or a read command from a host, and
during executing the access in the first state, control of executing overwriting of a post code among the plurality of post codes at the second storage area on a track at which the write head is located in the first state among the plurality of tracks.
14. A method for controlling a magnetic disk device including: a magnetic disk in which a first storage area and a second storage area in which a plurality of tracks is set are provided in a radial direction, a plurality of post codes for correcting positional displacement of the plurality of tracks being stored in the first storage area, a third storage area and a fourth storage area being provided in a circumferential direction in the second storage area; and a magnetic head including a write head that executes writing to the magnetic disk and a read head that executes reading from the magnetic disk, the method comprising:
reading the plurality of post codes from the first storage area; and
executing first processing of writing the plurality of read post codes in the third storage area of the second storage area,
wherein the executing the first processing includes executing, in a state where the write head is located on a first track among the plurality of tracks, both second processing of writing a first post code among the plurality of read post codes in the third storage area and third processing of writing user data in the fourth storage area or reading user data from the fourth storage area.
15. The method according to claim 14 ,
wherein the first post code is a post code for correcting positional displacement of a second track, and
the second track is a track at which the write head is located in a state where the read head is located on the first track.
16. The method according to claim 15 ,
wherein the executing the first processing includes acquiring an amount of positional displacement of a third track adjacent to the second track among the plurality of tracks and correcting the first post code on a basis of the amount of the positional displacement the third track, and
the second processing includes writing the corrected first post code.
17. The method according to claim 16 , further comprising:
generating a second post code for correcting the positional displacement of the third track on a basis of the acquired amount of the positional displacement of the third track; and
correcting the first post code through weighted addition of the first post code and the generated second post code.
18. The method according to claim 14 further comprising:
arranging the plurality of tracks in accordance with a first scheme; and
switching the first scheme between two second schemes, wherein
the plurality of post codes includes two sets of post codes, each of the two sets corresponding to a respective second schemes among the two second schemes, and
the executing the first processing includes
reading a set which correspond to a second scheme to which the first scheme is switched among the two sets from the first storage area and writing post codes included in the read set in the third storage area of the second storage area.
19. The method according to claim 15 further comprising:
arranging the plurality of tracks in accordance with a first scheme; and
switching the first scheme between two second schemes, wherein
the plurality of post codes includes two sets of post codes, each of the two sets corresponding to a respective second schemes among the two second schemes, and
the executing the first processing includes
reading a set which correspond to a second scheme to which the first scheme is switched among the two sets from the first storage area and writing post codes included in the read set in the third storage area of the second storage area.
20. The method according to claim 18 ,
wherein one of the two second schemes is a scheme in which the plurality of tracks is arranged so that data is written in a manner such that data of one track between two tracks which are adjacent to each other in a radial direction of the magnetic disk overlaps with part of data of the other track between the two tracks, and
the other of the two second schemes is a scheme in which the plurality of tracks is arranged so that data of two tracks which are adjacent to each other in the radial direction of the magnetic disk do not overlap with each other.