Patent Application
20120030510
1. Field of the Invention
The present invention relates to a power loss event in a hard disk drive.
2. Background Information
Hard disk drives are used to store data within a system. In the event of sudden power loss, for example when a user pulls the plug on an operating system, the system will include components that allow for writing of data within the disk drive. For example, the system may include a capacitor that stores enough energy to allow the drive to complete the writing of a disk sector. Such an approach is adequate for drives that have 512 byte sectors. If the sectors are expanded, for example to 4 Kbytes per sector, then such capacitors would not have enough power to allow the drive to write a complete sector or mark potentially corrupt sectors.
A hard disk drive that is connected to a non-volatile memory that includes data stored upon the occurrence of a power loss, the data having been designated to be stored in the hard disk drive in a previous time period. The hard disk drive includes a circuit that causes the data stored in the non-volatile memory to be written onto a disk of the drive.
Described is a hard disk drive that is coupled to a non-volatile memory. The non-volatile memory includes data that was designated to be stored in the hard disk drive in a previous time period. When a power loss event is detected the hard disk drive stores the track address of the last written track in non-volatile memory. When power is returned, the hard drive retrieves the last track address from the non-volatile memory. The data can then be rewritten onto the last track. Such an approach allows relatively large sectors of 4 Kbytes to be recaptured after a power loss event.
Referring to the drawings more particularly by reference numbers,
The disk drive 10 may include a plurality of heads 20 located adjacent to the disks 12. Each head 20 may have separate write and read elements. The write element magnetizes the disk 12 to write data. The read element senses the magnetic fields of the disks 12 to read data. By way of example, the read element may be constructed from a magneto-resistive material that has a resistance which varies linearly with changes in magnetic flux.
Each head 20 may be gimbal mounted to a suspension arm 26 as part of a head gimbal assembly (HGA). The suspension arms 26 are attached to an actuator arm 28 that is pivotally mounted to the base plate 16 by a bearing assembly 30. A voice coil 32 is attached to the actuator arm 28. The voice coil 32 is coupled to a magnet assembly 34 to create a voice coil motor (VCM) 36. Providing a current to the voice coil 32 will create a torque that swings the actuator arm 28 and moves the heads 20 across the disks 12.
The hard disk drive 10 may include a printed circuit board assembly 38 that includes one or more integrated circuits 40 coupled to a printed circuit board 42. The printed circuit board 40 is coupled to the voice coil 32, heads 20 and spindle motor 14 by wires (not shown).
The read/write channel circuit 58 is connected to a controller 64 through read and write channels 66 and 68, respectively, and read and write gates 70 and 72, respectively. The read gate 70 is enabled when data is to be read from the disks 12. The write gate 72 is enabled when writing data to the disks 12. The controller 64 may be a digital signal processor that operates in accordance with a software routine, including a routine(s) to write and read data from the disks 12. The read/write channel circuit 58 and controller 64 may also be connected to a motor control circuit 74 which controls the voice coil motor 36, and spindle motor 14 of the disk drive 10. The controller 64 may be connected to a non-volatile memory device 76. By way of example, the device 76 may be a read-only memory (“ROM”) that contains instructions that are read by the controller 64.
Decision block 116 determines if there is a power fault interrupt. If no, the writing process continues. If yes, the method continues to block 124 where the power write fault interrupt within the drive is disabled. The value of the write power fault flag is determined in decision block 126. If the flag is zero the process completes the writing process and ends. If the flag is set at 1 then the data saved in the non-volatile memory is removed in block 128 and the write process continues. A flag setting of 1 in this process indicates that an interrupt occurred but power was not lost. By way of example, steps 118-122 may be performed by the processor and the remaining steps may be performed by the disk drive controller.
While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.
