Mapping table management method for solid state disk and solid state disk

Abstract

The invention discloses a mapping table management method for a solid state disk and the solid state disk. The method is characterized in that an SCM is added into the solid state disk, a hard disk controller regards the SCM as a solid state disk data cache, and a mapping table used for recording a mapping relation between a specific physical address of an NAND and a logic address accessed by a host is created and stored in the SCM; and when the host writes host data into the solid state disk, the data is written into the SCM first to be cached, and the mapping table is updated synchronously after the data cached in the SCM is actually updated to the NAND or the mapping table is updated synchronously when the data is written into the SCM to be cached. By storing the mapping table in the SCM, the mapping table no longer needs to be stored in the NAND, occupation of space of the NAND is avoided, and therefore the problem of writing amplification caused by frequent updating of the mapping table is avoided. Meanwhile, the operation of loading an initial mapping table from the NAND after startup is omitted, and startup response delay is greatly shortened.

Description

technical field [0001] The invention relates to solid-state hard disk control technology, in particular to a solid-state hard disk mapping table management method and the solid-state hard disk. Background technique [0002] figure 1 It is a typical NAND composition diagram: DIE, a unit that can be operated independently and concurrently; Block, a unit that can be erased independently, and the data at each physical location in it must be erased before the next write; Page, read write unit. [0003] SSD (Solid State Drive) has been widely used in various occasions, and it is gradually replacing traditional HDD storage devices. In order to obtain the maximum concurrent writing speed of NAND, it is necessary to maintain a cache of user data in the memory (DRAM), and initiate concurrent writing to NAND after sufficient data is cached, so as to obtain the highest performance. Since the memory is a volatile device after power failure, the SSD system designed based on this scheme...

AI Technical Summary

Problems solved by technology

Since the memory is a volatile device after power failure, the SSD system designed based on this scheme will completely lose the data in the Cache after power failure, resulting in damage to user data.

[0004] figure 2 It is a schematic diagram of the conventional mapping table management mechanism; at present, the internal mapping table management strategy of most SSDs is: maintain a mapping table in the memory to describe the mapping relationship between the logical address of the host access unit and the physical address stored on the NAND; the logical address of the host access unit The data of 3 is stored in the physical address D. When the data is written into the NAND, the mapping table will be updated at the same time; the NAND is divided into two parts, one part stores the data, and the other part stores the mapping table; because the mapping table will be lost when power off, in order to To speed up the boot process, the mapping table needs to be periodically refreshed to the designated area of ​​NAND; the area where the mapping table is stored on the NAND takes up more and more space as the usage time increases, and garbage collection is required. NAND writing; at the same time, because NAND needs to store changes in the mapping table, it leads to additional write amplification, which affects the life and performance of SSD

[0005] Furthermore, after the system is powered off and powered on again, since the data in the memory has been lost, it is necessary to scan and load the mapping table from the NAND storage area to the DRAM first, and then the host access request can obtain the corresponding mapping table entry, resulting in The problem of slow response time after booting

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