TWI682395B - Redirecting method of unmapped address of solid state hard disk - Google Patents

Abstract

The invention discloses a method for redirecting unmapped addresses of a solid-state hard disk to provide a NAND memory. The NAND memory has several blocks, and each block has several pages. Select a block from the block of NAND memory. Select several pages from the selected block as "0" special pages, and write their data as "0", and select several pages as "1" special pages, and write their data as "1" ". Receive a request to read data from an address of a solid-state hard drive from the host, and then determine whether the address is an unmapped address. If the address is unmapped, pass "0" or "1" from the dedicated page of "0" or "1" to the host.

Description

Redirecting method of unmapped address of solid state hard disk

The invention relates to a solid-state hard disk, especially a method for redirecting unmapped addresses of the solid-state hard disk.

When a host wants to read data from unmapped addresses of a solid state drive (SSD), the host requires the solid state drive to provide "0" or "1". In order to cope with the request of the host, all the data in a part of NAND memory (dedicated part of "0") is written as "0", and in another part of NAND memory (dedicated part of "1") The information of is written as "1". Each time the host needs to read the data of an unmapped address, if the host requires "0" as the data of the unmapped address, the "0" is passed from the dedicated part of "0" to the host, if the host requests "1" "As unmapped data, "1" is passed from the dedicated part of "1" to the host. This procedure is called redirecting.

Referring to FIG. 4, in a conventional manner, the first page of a block of NAND memory is used as a dedicated part of "0", and the second page of the same block of NAND memory is used Used as a dedicated part of "1". At the request of the host, the data may be read many times from the dedicated part of "0" or the dedicated part of "1" of the NAND memory. This will inevitably lead to "read disturb", that is, when the number of data reads from a page reaches a value, the entire NAND memory will fail, even if other pages of the NAND memory are rarely used.

Referring to Figure 5, in another traditional way, a solid-state drive is used The first buffer of random access memory (RAM) is used as a dedicated part of "0", and the second buffer of random access memory is used as a dedicated part of "1". In this way, avoid "read disturb". However, in order to use random access memory to handle redirection, it causes some problems. First, it is necessary to use a random access memory with a large capacity, which inevitably increases costs. Secondly, the possibility of reading data from random access memory or NAND memory increases the complexity of software design.

In view of the above-mentioned problems of the conventional art, the object of the present invention is to provide an effective and cost-effective method for redirecting unmapped addresses of solid state hard disks.

To achieve the above objective, in the method for redirecting unmapped addresses of a solid state drive of the present invention, a NAND memory is provided. The NAND memory has several blocks, and each block has several pages. Select a block from the block of NAND memory. Select several pages from the selected block as "0" special pages, and write their data as "0", and select several pages as "1" special pages, and write their data as "1" ". Receive a request to read data from an address of a solid-state hard drive from the host, and then determine whether the address is an unmapped address. If this address is an unmapped address, pass "0" or "1" from the dedicated page of "0" or "1" to the host.

10‧‧‧Solid hard disk data storage device

Core 0,Core 1‧‧‧Central Processing Unit

12‧‧‧NAND memory

14‧‧‧ metadata

16‧‧‧NAND flash memory controller

18‧‧‧Flash memory conversion layer

20‧‧‧back

22‧‧‧Front end

24‧‧‧Data cache

26‧‧‧Host

S10~S28‧‧‧Step

Figure 1 is a block diagram of a solid state drive; Figure 2 is a flowchart of a method for redirecting unmapped addresses of a solid state drive according to a preferred embodiment of the present invention. This method is used in Figure 1 Data storage device; Figure 3 is based on the method shown in Figure 2, managed by NAND memory Block diagram; Figure 4 is a block diagram of a data storage device under a traditional solid-state hard disk unmapped address redirection method; and Figure 5 is another traditional solid-state hard disk unmapped address Block diagram of the data storage device under the redirection method.

The preferred embodiment of the unmapped address redirection method of the solid state drive of the present invention is described below with reference to related drawings. In order to facilitate the understanding of the present invention, the same symbols are used for the same elements.

Referring to FIG. 1, a solid-state hard disk 10 includes two central processing units (CPU) and a NAND memory 12. These two central processing units are called Core 0 and Core 1.

The central processing unit Core 0 executes several firmwares, such as system metadata (SysMeta) 14, NAND flash memory controller (NAND flash controller; NFC) 16, flash memory conversion layer (flash translation layer or FTL) 18. And the back (back end or BE) 20.

The central processing unit Core 1 executes several firmwares, such as front end (FE) 22 data and cache (data cache or DC) 24.

The NAND memory 12 has many blocks, and each block has many pages. In the preferred embodiment, these blocks form N groups, and each group has several blocks. In another embodiment, these blocks are not grouped into groups.

Referring to FIG. 2, the unmapped address redirection method (“program”) of the solid state drive of the preferred embodiment of the present invention is used for the solid state drive 10 shown in FIG. 1.

Referring to Figure 2 and Figure 3, at S10, the procedure starts.

At S12, the metadata 14 is executed to select a group from the N groups.

At S14, the metadata 14 calls the NAND flash memory controller 16, selects M/2 pages from the many pages of the selected group and writes their data as "0", and additionally selects M/2 pages and Write their data as "1". For convenience of description, this M page is called "dedicated page", M/2 page full of "0" is called "0" dedicated page, and M/2 page full of "1" is called "1" dedicated Page, the rest of the pages are called "normal pages". When a group is selected, the ordinary pages of the group are used to store data, that is, the data is written into the ordinary pages of the group.

At S16, the front end 22 receives a request to read data from the host 26. This requirement includes a logical address ("original logical address"). Therefore, the front end 22 prepares and transmits a request to the data cache 24. .

At S18, after receiving the request from the front end 22, the data cache 24 prepares and transmits a request to the flash memory conversion layer 18.

In S20, after receiving the request from the data cache 24, the flash memory conversion layer 18 converts the original logical address into the original physical address, and transmits a request to the back end 20.

At S22, the backend 20 determines whether the original physical address is an unmapped address.

If the original physical address is not an unmapped address, the procedure goes directly to S24, and the original physical address is transferred to the NAND flash memory controller 16.

If the original physical address is an unmapped address, the program first goes to S23 and then to S24.

At S23, the backend 20 obtains a redirected physical address from the metadata 14, and replaces the original physical address with the redirected physical address. And transfer the redirected physical address to the NAND flash memory controller 16.

At S24, the NAND flash memory controller 16 Address or redirect the physical address, transfer "0", "1" or other data to the host 26.

At S26, it is judged whether all the general pages of this group are full. If yes, the program goes to S27, otherwise the program goes to S28.

At S27, the metadata 14 selects another group.

At S28, the procedure ends.

Compared with the prior art, the present invention has several advantages. First, long life. "M" and "N" special pages are used to store "0" and "1", so "read disturb" is not likely to occur. Second, the cost is low, and the solid state drive 10 does not occupy the capacity of the random access memory, so it is not necessary to use a large-capacity and expensive random access memory. Third, the software complexity is low because the source of data is only NAND memory12.

The above are merely preferred embodiments for describing the present invention, and are not intended to limit the scope of the present invention. Equal changes made by a person of ordinary skill in the art based on the above embodiments, as well as changes well known to those skilled in the art, are still within the scope of the present invention.

10‧‧‧Solid hard disk data storage device

12‧‧‧NAND memory

14‧‧‧ metadata

16‧‧‧NAND flash memory controller

18‧‧‧Flash memory conversion layer

20‧‧‧back

22‧‧‧Front end

24‧‧‧Data cache

26‧‧‧Host

Claims (4)

A method for redirecting unmapped addresses of a solid state drive includes the following steps: providing a NAND memory, wherein the NAND memory has several blocks, and each block has several pages; from the area of the NAND memory Select a block from the block; select several pages from the selected block as "0" dedicated pages, and write all their data as "0", and select several additional pages from the selected block as "1" dedicated page, and write all its data as "1", other pages are regarded as ordinary pages; receive a request from a host (26) to read the data of a single address of the solid state drive (10); And judge whether the address is an unmapped address; if the address is an unmapped address, then transfer the "0" or "1" of the dedicated page of "0" or "1" to the host (26) . The method for redirecting unmapped addresses of a solid state drive as described in claim 1 further includes the following steps: determining whether the bits of the selected ordinary page of the block are written; if not, renew the area Block; and if so, choose another block. A method for redirecting unmapped addresses of a solid state drive, wherein a solid state drive includes a NAND memory (12), a meta data (14), a NAND flash memory controller (16), a flash memory Volume conversion layer (18), a back-end (20), a front-end (22), a data cache (24), the NAND memory (12) has many blocks, and each Each block has several pages. The method includes the following steps: (S12) execute the metadata (14) and select a block from the blocks; (S14) the metadata (14) call the NAND flash memory The controller (16) selects the M/2 page from many pages of the selected block as the "0" special page, and writes its data as "0", and additionally selects the M/2 page as " 1" dedicated page, and write its data as "1", other pages are regarded as ordinary pages; (S16) The front end (22) receives a request to read data from a host (26), where this request includes an original Logical address, and the front end (22) prepares and sends a DC request to the data cache (24); (S18) the data cache (24) prepares and sends an FTL request to the flash memory conversion layer ( 18); (S20) The flash memory conversion layer (18) converts the original logical address into an original physical address, and sends a request to the back-end (20); (S22) the back-end (20) Determine whether the original physical address is an unmapped address; (S24) If the original physical address is not an unmapped address, transfer the original physical address to the NAND flash memory controller (16); ( S23) If the original physical address is an unmapped address, the back-end (20) obtains a redirected physical address from the metadata (14), replaces the original physical address, and redirects the redirected physical address Address to the NAND flash memory controller (16); (S24) the NAND flash memory controller (16) from the original physical address or The redirected physical address transmits "0", "1" or other data to the host (26). The method for redirecting unmapped addresses of a solid state drive as described in claim 3, further includes the following steps: (S26) judging whether the ordinary pages of the block are filled; (S27) if yes, the metadata (14 ) Choose another group. (S28) Otherwise, the procedure ends.

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