Hard disk drive and data refresh method

According to one embodiment, a hard disk drive includes a detecting circuit configured to detect abnormality of a supply voltage. The hard disk drive also includes a refresh controller configured to, when the abnormality of the supply voltage is detected during a data refresh process in sector units to a magnetic disk, finish the data refresh process to a sector after writing of data to a data area is finished, the data area to which the writing is performed when the abnormality of the supply voltage is detected, without stepping over a servo area.

FIELD

This embodiment generally relates to a hard disk drive and a data refresh method.

BACKGROUND

In a conventional hard disk drive, recording density becomes higher with higher capacity and an interval between adjacent tracks on a disk becomes narrower. Therefore, when data is magnetically written to the track, data of the adjacent track might be magnetically deteriorated. In a recent hard disk drive, data refresh (rewrite) is performed for recovering data deterioration in the adjacent track due to data write operation. For example, the data written to the track adjacent to the track in which the number of times of data writing reaches a prescribed number is read and the read data is rewritten to the same track.

When power shutdown or a voltage drop occurs during the writing to the disk, the hard disk drive finishes the writing after writing to the end of one sector to which the writing is performed at that time. However, when the sector length is long, there is possibility that the writing to one sector cannot be completed due to the voltage shutdown or voltage drop and write data is interrupted in a halfway position of the sector. In the case of the data refresh also, in the hard disk drive, when the power is shut down during operation to rewrite the data read from the track to be refreshed to the same track, the data might be lost. As a measure against this, there is a case in which the read data to be refreshed is stored in a backup area in advance and then rewritten to the track from which this is read.

However, when the backup is performed, the data refresh takes time.

DETAILED DESCRIPTION

In general, according to one embodiment, a hard disk drive includes a magnetic disk on which data is recorded in a data area separated with a servo area. The hard disk drive also includes a control unit configured to control reading and writing of the data from and to the magnetic disk. The control unit includes a detecting circuit configured to detect abnormality of a supply voltage supplied to the control unit. The control unit also includes a refresh controller configured to, when the abnormality of the supply voltage is detected by the detecting circuit during a data refresh process in sector units to the magnetic disk, finish the data refresh process to the sector after the writing of the data to the data area is finished, the data area to which the writing is performed when the abnormality of the supply voltage is detected, without stepping over the servo area.

Exemplary embodiments of a hard disk drive and data refresh method will be explained below in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments.

First Embodiment

FIG. 1is a diagram illustrating a configuration example of a hard disk drive10of this embodiment. The hard disk drive10includes a magnetic disk1, a head2, a head IC (integrated circuit)3, and a control unit4. The control unit4includes a read/write channel5, a refresh controller6, a supply voltage abnormality detecting circuit7, and a storage unit8.

The data is recorded on the magnetic disk1being a recording medium in the data area separated with the servo area. The head2includes a read head and a write head to read/write the data from/to the magnetic disk1. The head IC3amplifies a signal read from the magnetic disk1by the head2and transmits the signal to the read/write channel5of the control unit4. The head IC3converts a write signal from the read/write channel5of the control unit4to a write current and transmits the current to the head2. The control unit4controls the reading/writing of the data from/to the magnetic disk1and controls the data refresh process to the magnetic disk1.

The read/write channel5executes a signal process of the data read from/written to the magnetic disk1. The refresh controller6controls the data refresh process to the magnetic disk1. The supply voltage abnormality detecting circuit7detects the abnormality of the supply voltage supplied to the hard disk drive10. When the data refresh process to the magnetic disk1is interrupted, the storage unit8stores information about a sector in which the data refresh process is interrupted. The storage unit8also temporarily stores the read data in the data refresh process.

In the hard disk drive10, the magnetic disk1, the head2, and the head IC3have general configurations. InFIG. 1, a configuration related to the data refresh process in this embodiment is illustrated as a configuration of the hard disk drive10and a general configuration of a driver IC and the like is omitted.

The data refresh process of this embodiment is subsequently described. First, operation in a case in which the abnormality is detected in the supply voltage supplied to the hard disk drive10is described about difference from an operation of a conventional hard disk drive. In general, in the magnetic disk1, the data areas and servo areas are alternatively arranged on a plurality of tracks. The data area is the area on which the data is recorded and a servo signal for positioning of the head2is recorded on the servo area. Meanwhile, in the following description, write operation to the magnetic disk1is referred to as disk write.

FIG. 2is a diagram illustrating a state of the sector in a case in which the supply voltage abnormality is detected during the disk write. An upper side is a state when the supply voltage abnormality is detected and a lower side is a state after the disk write is finished. Servo represents the servo area and S1to S3represent the data areas. One sector is a unit of the writing of the data to the magnetic disk1. Although the data area and the servo area actually have curved shapes in a circumferential direction of the magnetic disk1, they are herein indicated to have linear shapes for easier comparison.

In the conventional hard disk drive, when power shutdown and the like occurs and the supply voltage abnormality is detected during the disk write (point a), the process is normally finished after the writing to a sector break of one sector to which the disk write is performed (point b). However, when one sector is long, the writing cannot be performed to the end of one sector due to a supply voltage drop and write data might be interrupted in a halfway position. In this case, the sector in question becomes unreadable and the data is lost.

In the hard disk drive10according to this embodiment, only in the disk write during the data refresh process, when the power shutdown and the like occurs and the supply voltage abnormality is detected during the disk write (point a), the writing is not performed to the sector break of one sector to which the disk write is performed. The hard disk drive10finishes the disk write when the writing to the data area is completed, the data area to which the disk write is performed when the supply voltage abnormality is detected separated with a servo split break, that is to say, the servo area of one sector to which the disk writing is performed (point c). The hard disk drive10finishes the data refresh process without stepping over the servo area. According to this, when the abnormality such as the power shutdown occurs during the data refresh process, the disk write is not finished in a halfway position of the data area, so that data loss may be prevented, and it becomes possible to normally read the sector in question.

In a case of the data refresh process, the already recorded data is rewritten and the already recorded data remains in the data area after a split stop position. Therefore, in the hard disk drive10, only in the disk write during the data refresh process, the sector in which the disk write is interrupted can be normally read if the writing is correctly performed to a point of the split break.

That is to say, in the hard disk drive10according to this embodiment, the data is not lost at the time of the data refresh process. Therefore, it is not required to back up the data during the data refresh process in the magnetic disk1or a non-volatile memory not illustrated inFIG. 1when the data refresh process is started, so that time for the writing at the time of the backup of the data is not required and it becomes possible to perform the data refresh process at a higher speed than in the conventional drive.

FIG. 3is a flowchart illustrating the data refresh process by the hard disk drive10of this embodiment.

First, in the hard disk drive10of this embodiment, the refresh controller6of the control unit4starts the data refresh process to the data of a track being a refresh process target to the magnetic disk1through the read/write channel5(step S11).

The supply voltage abnormality detecting circuit7of the control unit4monitors the supply voltage supplied to the control unit4of the hard disk drive10to confirm whether the supply voltage abnormality is detected (step S12).

When the abnormality of the supply voltage is not detected by the supply voltage abnormality detecting circuit7(step S12: No), the refresh controller6confirms whether the data refresh process of all the sectors in the target track is finished (step S13). When this is not finished for the target sector (step S13: No), the refresh controller6returns to step S11to continue the data refresh process.

On the other hand, when the abnormality of the supply voltage is detected by the supply voltage abnormality detecting circuit7(step S12: Yes), the refresh controller6finishes the data refresh process in the middle. At that time, the refresh controller6finishes the disk write when the writing to the servo split break of one sector to which the disk write is performed is performed through the read/write channel5. That is to say, the data refresh process is finished when the writing is completed for the data area to which the disk write is performed when the supply voltage abnormality is detected (step S14).

When the data refresh process of all the sectors in the target track is finished (step S13: Yes), the refresh controller6performs control to finish the data refresh process (step S15).

Meanwhile, in the hard disk drive10, when the data refresh process is finished in the middle of the sector (step S14), information about the sector may be stored to be used when the data refresh process is started next time.

Suppose that the hard disk drive10performs the data refresh process in track units and the data refresh process is finished in the middle of the sector because the supply voltage abnormality is detected. In the hard disk drive10, if the data refresh process is finished in the middle of the sector just after the data refresh process is started, time loss is not significant even when the data refresh process of the target track is restarted from the first. On the other hand, in the hard disk drive10, when the data refresh process of the target track is finished in the middle of the sector just before the data refresh process finishes, it is not efficient to restart the data refresh process of the target track from the first.

Therefore, the refresh controller6stores information which identifies the sector in the middle of which the data refresh process is finished or information which identifies the data area in the middle of which the data refresh process is finished in the storage unit8as identification information when the data refresh process is finished in the middle of the sector. Then, the refresh controller6reads the identification information from the storage unit8and starts the data refresh process from the sector in the middle of which the data refresh process is finished or the data area (data area in which the data refresh process is not finished) next to the data area in which the data refresh process is finished. According to this, the hard disk drive10may efficiently perform the data refresh process.

According to the first embodiment, when the hard disk drive10detects the abnormality of the supply voltage to be supplied in the data refresh process, the hard disk drive10does not perform the writing to the sector break of one sector to which the disk write is performed but the hard disk drive10finishes the disk write when the hard disk drive10completes the writing to the data area separated with the servo split break, that is to say, the servo area of one sector to which the data writing is performed. According to this, the data is not lost at the time of the data refresh process, so that it is not required to back up the data when the data refresh process is started, therefore, it is possible to obtain an effect that the speed of the data refresh process is increased and speedup is realized as compared to the conventional drive.