US-12625776-B2 - Magnetic disk drive

US12625776B2US 12625776 B2US12625776 B2US 12625776B2US-12625776-B2

Abstract

According to one embodiment, a magnetic disk drive includes a flash memory adopting a Serial NAND that includes a plurality of Blocks. The magnetic disk drive determines one or more first Blocks to be used for write at backup, among the plurality of Blocks, based on a write time per the Block in the Serial NAND. The magnetic disk drive backs up data in a nonvolatile memory to the Serial NAND using a counter electromotive force of a spindle motor.

Inventors

Keigo SOGABE

Assignees

KABUSHIKI KAISHA TOSHIBA
TOSHIBA ELECTRONIC DEVICES & STORAGE CORPORATION

Dates

Publication Date: 20260512
Application Date: 20240726
Priority Date: 20240322

Claims (8)

1 . A magnetic disk drive, comprising: a flash memory adopting a Serial NAND that includes a plurality of Blocks, wherein the magnetic disk drive backs up data in a volatile memory to the Serial NAND using a counter electromotive force of a spindle motor and determines one or more first Blocks to be used for write at backup, among the plurality of Blocks, based on a write time per the Block in the Serial NAND, determines a write order at backup to the one or more first Blocks based on the write time, and preliminarily sorts addresses of the first Blocks in the write order and stores the sorted addresses in the serial NAND.
2 . The magnetic disk drive of claim 1 , wherein the magnetic disk drive measures the write time.
3 . The magnetic disk drive of claim 1 , wherein the magnetic disk drive identifies a second Block of the plurality of Blocks, which is unavailable, as distinct from the first Block.
4 . The magnetic disk drive of claim 3 , wherein the second Block is unavailable when the second Block has a write failure or when the write time of the second Block exceeds a write time standard of the magnetic disk drive.
5 . The magnetic disk drive of claim 3 , wherein the write order is an order in which write to the first Blocks is executed in an ascending order of a write frequency.
6 . The magnetic disk drive of claim 5 , wherein the magnetic disk drive counts the write frequency of the first Block.
7 . A magnetic disk drive comprising: a flash memory adopting a Serial NAND that includes a plurality of Blocks; and a PLP information table including a backup execution count, a Block write time measurement result in the Serial NAND, a result of executing address sort for the Blocks in an ascending order of the write time, a Block availability result, and a write frequency (usage count of the Block), wherein the magnetic disk drive backs up data in a volatile memory to the Serial NAND using a counter electromotive force of a spindle motor and determines one or more first Blocks to be used for write at backup, among the plurality of Blocks, based on a write time per the Block in the Serial NAND.
8 . The magnetic disk drive of claim 7 , wherein the magnetic disk drive determines whether the PLP information table is to be updated or not based on the backup execution count.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2024-046340, filed Mar. 22, 2024, the entire contents of which are incorporated herein by reference. FIELD Embodiments described herein relate generally to backup data processing in a magnetic disk drive. BACKGROUND The magnetic disk drive comprises Power Loss Protection (PLP) function as a technique to back up cache data, which is stored in a volatile memory, in a nonvolatile memory at the time of a power loss. Nonvolatile memories used for the PLP function have adopted a Serial NOR as a flash memory. The Serial NOR involves long data write time. Thus, sufficient amount of data may not be backed up. That is, backup data size is not maintained in some cases. By adopting a Serial NAND enabling large-capacity/high speed access, improvement in HDD performance such as increase in backup data size can be expected. However, products using the Serial NAND may generate Blocks involving write failure (Bad Blocks) and may decrease the backup data size at the time of activating the PLP. The present embodiment provides a magnetic disk drive comprising a PLP function to back up data to a flash memory adopting the Serial NAND. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a configuration of a magnetic disk drive of an embodiment. FIG. 2 is a timing chart illustrating operations of a PLP function of the magnetic disk drive of the present embodiment. FIG. 3 is a schematic view illustrating data configuration of a nonvolatile memory (Serial NAND) in the magnetic disk drive of the present embodiment. FIG. 4 is a flowchart showing processing operations in the magnetic disk drive of the present embodiment. FIG. 5A shows an example of a PLP information table of the Serial NAND included in the magnetic disk drive of the present embodiment in a case where a backup execution count is 0. FIG. 5B shows an example of the PLP information table of the Serial NAND included in the magnetic disk drive of the present embodiment in a case where the backup has been executed. FIG. 6 is an imaginary view of an address in a case where the magnetic disk drive of the present embodiment sorts Blocks in ascending order of write time. FIG. 7 is a schematic view illustrating the Serial NAND in a case where NG occurs in write into Blocks in the Serial NAND in the magnetic disk drive of the present embodiment. FIG. 8 is a flowchart showing processing operations in the magnetic disk drive of the embodiment while the PLP is activated. DETAILED DESCRIPTION In general, according to one embodiment, a magnetic disk drive comprises a flash memory adopting a Serial NAND comprising a plurality of Blocks. The magnetic disk drive determines one or more first Blocks to be used for backup, among the plurality of Blocks, based on write time per each of the Blocks in the Serial NAND. The magnetic disk drive backs up data, which is stored in a nonvolatile memory, in the Serial NAND using counter electromotive force of a spindle motor. First Embodiment The present embodiment shows a magnetic disk drive comprising a PLP function adopting a Serial NAND. The PLP function is a function to back up unwritten data that are stored in a volatile memory such as DRAM to a nonvolatile memory in the magnetic disk drive at the time of power loss. The present embodiment is an example of a magnetic disk drive that predicts a risk at which Bad Block, which cannot be used in the Serial NAND, occurs and avoids access to a Block involving high risk at the time of executing PLP. The present embodiment utilizes characteristic that the Block involves longer write time in the Serial NAND is more likely to become Bad Block. FIG. 1 shows a configuration of a magnetic disk drive of an embodiment. A magnetic disk drive 1 is a storage device comprising a magnetic disk 11 on which data is written and read (hereinafter simply referred to as a disk 11 in some cases). The magnetic disk drive 1 further comprises a processor having computing function such as arithmetic processing (for example, a processing unit such as a CPU and a microprocessor), and various types of memories. The magnetic disk drive 1 outputs data to a host system 2 and writes data input from the host system 2 into the disk 11 based on a command received from the host system 2 to which the disk drive 1 is connected and the like. The magnetic disk drive 1 of the present embodiment adopts a system in which received data is temporally stored in a buffer memory before writing this data received from the host system 2 into the disk 11. The disk drive 1 uses, for example, a DRAM of a volatile memory 70 to be described later as the buffer memory. The method using the buffer memory increases data transmission speed from the host system 2 and the like and thus improves throughput of the magnetic disk drive 1. The host system 2 is, for example, a PC body and outputs a read command, which is a read instr