TW201717024A - Data storage device and data maintenance method thereof - Google Patents

Abstract

The present invention provides a data storage device. The data storage device includes a flash memory and a controller. The flash memory includes a plurality of blocks, and each of the blocks includes a plurality of pages. When the data storage device is resumed from a power off state, the controller selects a first block that is the last written before the power off state from the blocks, and writes data of a plurality of first pages of the first block into a plurality of second pages of the first block.

Description

Data storage device and data maintenance method thereof

The present invention relates to a data storage device, and more particularly to a data storage device for maintaining data after a power outage event.

Flash memory is a popular non-volatile data storage device that is electrically erased and programmed. For example, NAND FLASH, which is not a gate type, is often used as a memory card, a universal flash memory device, a solid state drive (SSD), and an embedded flash. Memory module (eMMC)...etc.

A flash memory (eg, NAND FLASH) storage array includes a plurality of blocks, wherein a floating gate transistor can be used to form a flash memory. A floating gate in a floating gate transistor that captures charge to store data. However, during the write process, an unexpected power down event can corrupt the data on the page being written. Therefore, how to maintain data after a power outage is an important issue.

The data storage device and the data maintenance method provided by the present invention can rewrite potentially damaged data into the same block after a power failure event.

The invention provides a data storage device comprising a flash memory and a controller. The flash memory includes a plurality of blocks, each block including a plurality of blocks page. When the data storage device replies from a power-off event, the controller selects one of the first blocks to be written in the block before the power-off event, and the first page in the first block is The data is written to other plural second pages outside the first page in the first block.

In an embodiment, the first block further includes a complex digital element line, and the first block is a second-order storage unit block (MLC block), wherein each word line of the first block is used to control the first block. Two pages in a block. When the data storage device replies from the power-off event, the controller is further configured to select, in the page of the first block, the last page to be written before the power-off event as a reference page, and according to the word line The first word line used to control one of the reference pages determines the first page. The first page is a page having valid data in a plurality of third pages controlled by the first word line and the at least one second word line arranged in front of the first word line. In another embodiment, the controller is further configured to write dummy data to a page in the third page that does not have valid data.

In another embodiment, the controller is further configured to determine whether a backup block has a backup of the first page, and write the data in the first page that does not have the backup in the backup block to the backup block. In addition, the controller is further configured to write the second page according to the data stored in the backup block corresponding to the first page to write the data of the first page to the second page, wherein the data protection capability of the backup block Higher than the first block. In addition, in an embodiment, the first block is a second-order storage unit block (MLC block), and the backup block is a single-stage storage unit block (SLC block).

The present invention further provides a data maintenance method suitable for a data storage device having a flash memory, wherein the flash memory includes a plurality of blocks. And each block includes a plurality of pages. The data maintenance method includes: when the data storage device replies from a power-off event, selecting, in the block, one of the first blocks to be written before the power-off event; and the plurality of blocks in the first block The data in one page is written into the other plural second page outside the first page in the first block.

In an embodiment, the first block further includes a complex digital element line, and the first block is a second-order storage unit block (MLC block), wherein each word line of the first block is used to control the first block. Two pages in a block. The data maintenance method further includes: selecting, in the page of the first block, the last page to be written before the power-off event as a reference page; and selecting one of the reference pages according to the character line. A word line determines a first page, wherein the first page is a page having valid data in a plurality of third pages controlled by the first word line and at least one second word line arranged in front of the first word line . In addition, the data maintenance method further includes writing dummy data to a page on the third page that does not have valid data.

In another embodiment, the data maintenance method further includes: determining whether a backup block has a backup of the first page; and writing the data in the first page that does not have a backup in the backup block to the backup block. The step of writing the information in the first page in the first block to the other second page outside the first page in the first block further includes: according to the data corresponding to the first page stored in the backup block, The second page is written to write the data of the first page to the second page, wherein the data protection capability of the backup block is higher than the first block.

100‧‧‧Electronic system

120‧‧‧Host

140‧‧‧Data storage device

160‧‧‧ Controller

162‧‧‧ arithmetic unit

164‧‧‧Permanent memory

166‧‧‧ random access memory

180‧‧‧Flash memory

LSB‧‧ strong page

MSB‧‧‧ weak page

WL0~WLM‧‧‧ character line

Or_P0~Or_PM‧‧‧Original page

P0~PN, P0~PX‧‧‧ page

Block B1‧‧‧

BU_B‧‧‧Backup block

POR‧‧‧ power outage

S600~S604, S700~S716‧‧‧ steps

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram of one embodiment of an electronic system provided by the present invention.

Figure 2 is a block diagram of one embodiment of a block provided by the present invention.

Figure 3 is a schematic diagram of one of the data movements provided by the present invention.

Figure 4 is a schematic illustration of another data transfer provided by the present invention.

Figure 5 is a schematic view showing another data transfer provided by the present invention.

Figure 6 is a flow chart of an embodiment of a data maintenance method provided by the present invention.

Figure 7 is a flow chart showing another embodiment of another data maintenance method provided by the present invention.

The apparatus and method of use of various embodiments of the present invention are discussed in detail below. However, it is to be noted that many of the possible inventive concepts provided by the present invention can be implemented in various specific ranges. These specific examples are only intended to illustrate the apparatus and methods of use of the present invention, but are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram of one embodiment of an electronic system provided by the present invention. The electronic system 100 includes a host 120 and a data storage device 140. The data storage device 140 includes a flash memory 180 and a controller 160, and is operable according to commands issued by the host 120. The controller 160 includes an arithmetic unit 162, a permanent memory (e.g., read only memory ROM) 164, and a random access memory (RAM) 166. The permanent memory 164 and the stored code and data constitute a firmware, which is executed by the operation unit 162, so that the controller 160 controls the flash memory 180 based on the firmware. Random access memory (RAM) 166 is used to load code and parameters to provide controller 160 based on the loaded code and Parameter action.

Flash memory 180 includes a plurality of blocks, each block including a plurality of pages. It is worth noting that the flash memory 180 is erased in the smallest unit of the block, and the page is written in the smallest unit. In addition, the flash memory 180 further includes complex digital lines and complex bit lines adjacent to each other, wherein each of the word lines is used to control at least one page to select a page to be read. For example, when the block in the flash memory 180 is a Single-Level Cell (SLC), one word line is used to control one page. When the block in the flash memory 180 is a Multi-Level Cell (MLC), one word line is used to control a strong page LSB (strong page) and a weak page MSB (weak page). . When the block in the flash memory 180 is a Triple-Level Cell (TLC), one word line is used to control a strong page LSB (strong page) and a medium page CSB (middle page). And a weak page MSB (weak page), but the invention is not limited thereto. In detail, when the block in the flash memory 180 is a multi-level storage unit, a page controlled by a word line in the block can be programmed into a strong page LSB (strong page ) and a weak page MSB (weak page). When the block in the flash memory 180 is a third-order storage unit, a page controlled by a word line in the block can be programmed into a strong page LSB (strong page), one medium The page CSB (middle page) and a weak page MSB (weak page).

After the controller 160 writes the flash memory 180 again and the data storage device 140 experiences a power-off event, the controller 160 checks whether the data of a particular page being written at the time of the power-off event is detected. damage. in In some cases, although the controller 160 can successfully read data from a particular page, the data in a particular page has become unstable due to attacks from power outage events. In other words, after the controller 160 reads a specific page after a certain period of time, the data in the specific page may not be successfully read. It should be noted that in the present invention, as long as the data of the repair error bit can be corrected via error correction or repeated reading, it is a material that can be successfully read. Therefore, in some embodiments, the controller 160 writes the data of the specific page successfully read into another block after the self-power-off event reply, and the stability of the data is ensured. However, the above method consumes more blocks and also increases the number of erasures of the blocks.

In view of this, the present invention proposes an embodiment to improve the above problems. In this embodiment, when the data storage device 140 replies from a power-off event, the controller 160 selects one of the first blocks to be written in the block before the power-off event, and the first region is to be written. The data in the first plurality of pages in the block is written into the other plural second pages outside the first page in the first block. As described above, the controller 160 writes the data of the first page to the second page in the same first block to reduce the consumption of the block.

It should be noted that, in an embodiment, the flash memory 180 has a backup block, wherein the backup block has higher data protection capability than the first block B1. When the controller 160 writes to the flash memory 180, the data is written on the backup block and then written into the block. Therefore, in this embodiment, before writing the data in the first page to the second page, the controller 160 is further configured to determine whether the backup page has a backup of the first page, and the first page is in the backup area. The block does not have the data of the backup person written into the backup block, and according to the data stored in the backup block corresponding to the first page, the second page is written to the first page. It is written to the second page. As described above, the controller 160 protects the data by first writing the data in the backup block and preventing other power down events from occurring.

In one embodiment, the majority of the blocks in the flash memory (the first block) are a second-order memory cell block (MLC block), and the flash memory 180 has a single-stage memory cell region. A backup block of a block (SLC block), wherein the data protection capability of the single-stage storage unit block is higher than that of the second-order storage unit block, but the invention is not limited thereto. In other embodiments, the first block may be a multi-level storage unit block (TLC block), and the backup block may be a single-order storage unit block or a second-order storage unit block, and the number of backup blocks may be More than one. In this embodiment, in order to find the unstable first page, the controller 160 is further configured to select, in the page of the first block B1, the last page written before the power-off event as a reference page. And determining the first page according to the first character line in the word line for controlling one of the reference pages. In detail, the first page is a page having valid data in a plurality of third pages controlled by the first word line and the at least one second word line arranged in front of the first word line. In another embodiment, the controller 160 is further configured to write dummy data into a page of the third page that does not have valid data to stabilize the first block, wherein the redundant data may be a predetermined one. Invalid data or random data does not make any sense.

In detail, as shown in FIG. 2, the block B1 has the original pages Or_P0 to Or_PM, and the original pages Or_P0 to Or_PM are controlled by the word lines WL0 to WLM, respectively. In this embodiment, the block B1 is a multi-level storage unit. Therefore, the controller 160 can program each original page Or_P0~Or_PM into a strong page LSB and a weak page MSB, wherein the original page is programmed into two pages (strong page LSB and one weak page MSB). Originally operated The original page size for a single-stage storage unit is twice as large. It should be noted that, in an embodiment, based on the specific flash memory characteristics, the controller 160 programs the original pages Or_P0~Or_PM in a predetermined order to form the pages P0~PN, where the order is established. To: first write the strong page LSB of the original page Or_P0 to form the page P0, then write the strong page LSB of the original page Or_P1 to form the page P1, and then the weak page of the original page Or_P0 The MSB writes to form page P2, then writes the strong page LSB in the original page Or_P2 to form page P3, then writes the weak page MSB in the original page Or_P1 to form page P4, and so on. Therefore, for the controller 160, the order of the pages P0 to PN in the block B1 is as shown in FIG. It is to be noted that the number of pages P0 to PN is twice that of the original page Or_P0 to Or_PM, but the present invention is not limited thereto.

Figure 3 is a schematic diagram of one of the data movements provided by the present invention. Before the power-off event occurs, the controller 160 sequentially writes the data DATA0~DATA10 into the pages P0~P10 in the block B0, wherein the block B0 is the second-order storage unit block (MLC) as shown in FIG. Block). In order to prevent the strong page MSB controlled by the same word line from being damaged during the writing to the weak page LSB in the block B1, the controller 160 writes the data of the strong page MSB to the backup block BU_B first. , write strong page MSB. Therefore, the pages P0 to P5 in the backup block BU_B sequentially have the data DATA0, the data DATA1, the data DATA3, the data DATA5, the data DATA7, and the data DATA9, as shown in part (A) of FIG. When the controller 160 is writing the material DATA10 to the page P10 of the block B1, a power-off event POR occurs. Then, when the data storage device 140 replies from the power-off event, the controller 160 selects the power-off in the block of the flash memory. The last block B1 to be written before the event is used as the first block. Next, the controller 160 selects the last page P10 to be written before the power-off event as a reference page in the pages P0~PN of the first block B1, and selects from the word line WL0~WLM for control. The word line WL4 of the reference page P10 is taken as the first word line, and the first word line WL4 and the two word lines WL2 WL WL3 (second word line) arranged in front of the first word line are selected. The page with valid data in the plural pages P3, P5~P8 and P10 controlled is used as the first page. As described above, the first page is pages P3, P5~P8, and P10. Next, the controller 160 determines whether there is a backup of the first page P3, P5~P8, and P10 in the backup block BU_B. In this embodiment, the backup block BU_B has only the data DATA3 of the first page P3, the data DATA5 of the first page P5, and the data DATA7 of the first page P7, and the backup block BU_B has no data DATA6 of the first page P6, One page P8 data DATA8 and the first page P9 data DATA9. Therefore, the controller 160 then writes the data DATA6, DATA8, and DATA9 of the first pages P6, P8, and P9 into the pages P6 to P8 of the backup block BU_B, respectively, as shown in part (B) of FIG. Since the pages P3, P5 to P8, and P10 controlled by the first word line WL4 and the second word line WL2 to WL3 have valid data. Therefore, the controller 160 does not have to write dummy data into the block B1. Then, the controller 160 records the data DATA3 of the first page P3, P5~P8, P10 according to the data DATA3, DATA5~DATA8, DATA10 stored in the backup block BU_B corresponding to the first page P3, P5~P8, P10, DATA5~DATA8 and DATA10 are written in the second page P11~P16 of the first block B1, as shown in part (C) of Fig. 3.

Figure 4 is a schematic illustration of another material transfer provided by the present invention. Figure. In detail, before the power-off event occurs, the controller 160 sequentially writes the data DATA0~DATA10 into the pages P0~P10 in the block B0, wherein the block B0 is the second-order storage unit as shown in FIG. Block (MLC block). In order to prevent the strong page MSB controlled by the same word line from being damaged during the writing to the weak page LSB in the block B1, the controller 160 writes the data of the strong page MSB to the backup block BU_B first. , write strong page MSB. However, due to the rules of writing, some strong pages are not backed up in the backup block BU_B. Therefore, in this embodiment, the pages P0 to P4 in the backup block BU_B sequentially have the data DATA0, the data DATA1, the data DATA3, the data DATA7, and the data DATA9, as shown in part (A) of FIG. When the controller 160 is writing the material DATA10 to the page P10 of the block B1, a power-off event POR occurs. Next, when the data storage device 140 replies from the power-off event, the controller 160 selects the pages P3, P5-P8, and P10 as the first page according to the above rules. Next, the controller 160 determines whether there is a backup of the first page P3, P5~P8, and P10 in the backup block BU_B. In this embodiment, the backup block BU_B has only the data DATA3 of the first page P3 and the data DATA7 of the first page P7, and the backup block BU_B has no data DATA5 of the first page P5, and the data DATA6 of the first page P6, the first page One page P8 data DATA8 and the first page P9 data DATA9. Therefore, the controller 160 then writes the data DATA5, DATA6, DATA8, and DATA9 of the first page P5, P6, P8, and P9 into the pages P5 to P8 of the backup block BU_B, respectively, as shown in part (B) of FIG. Show. Since the pages P3, P5 to P8, and P10 controlled by the first word line WL4 and the second word line WL2 to WL3 have valid data. Therefore, the controller 160 does not have to write dummy data into the block B1. Then, the controller 160 is stored in the standby The data DATA3, DATA5~DATA8, and DATA10 corresponding to the first page P3, P5~P8, and P10 in the block BU_B are written into the first page P3, P5~P8, and P10 data DATA3, DATA5~DATA8, and DATA10. The second page P11~P16 of a block B1 is as shown in part (C) of Fig. 4.

Figure 5 is a schematic illustration of another data transfer provided by the present invention. Before the power-off event occurs, the controller 160 sequentially writes the data DATA0~DATA7 into the pages P0~P7 in the block B0, wherein the block B0 is the second-order storage unit block (MLC) as shown in FIG. Block). In order to prevent the strong page MSB controlled by the same word line from being damaged during the writing to the weak page LSB in the block B1, the controller 160 writes the data of the strong page MSB to the backup block BU_B first. , write strong page MSB. However, based on specific write rules, some strong page MSBs may not be backed up in the backup block BU_B, such as the data DATA5 of page P5. In this embodiment, the pages P0 to P5 in the backup block BU_B sequentially have the data DATA0, the data DATA1, the data DATA3, and the data DATA7, as shown in part (A) of FIG. When the controller 160 is writing the material DATA7 to the page P7 of the block B1, a power-off event POR occurs. Then, when the data storage device 140 replies from the power-off event, the controller 160 selects the last block B1 to be written as the first block in the block of the flash memory before the power-off event. Next, the controller 160 selects the last page P7 to be written before the power-off event as a reference page in the pages P0~PN of the first block B1, and selects from the word lines WL0~WLM for control. The word line WL4 of the reference page P7 is taken as the first word line, and the first word line WL4 and the two word lines WL2 WL WL3 (second word line) arranged in front of the first word line are selected. The pages with valid data in the controlled plural pages P3, P5~P7 and P10 are made For the first page. In this embodiment, only pages P3 and P5~P7 of the pages P3, P5~P8, and P10 have valid data, and the pages P8 and P10 do not have valid data. As described above, the first page is page P3 and P5~P7. Next, the controller 160 determines whether there is a backup of the first page P3 and P5~P7 in the backup block BU_B. In this embodiment, the backup block BU_B has only the data DATA3 of the first page P3 and the data DATA7 of the first page P7, and the backup block BU_B has no data DATA5 of the first page P5 and the data DATA6 of the first page P6. Therefore, the controller 160 then writes the data DATA5 and DATA6 of the first page P5 and P6 into the pages P4 to P5 of the backup block BU_B, respectively, as shown in part (B) of FIG. Since the pages P3, P5 to P7 and P10 of the pages P3, P5 to P7 and P10 controlled by the first word line WL4 and the second word line WL2 to WL3 do not have valid data. Therefore, the controller 160 writes dummy data to the pages P8 and P10 of the block B1 to prevent the valid data from being written to the pages P8 and P10 which are unstable after the power-off attack, as shown in the fifth figure ( C) is shown. Then, the controller 160 writes the data DATA3, DATA5~DATA7 of the first page P3, P5~P7 into the first page according to the data DATA3, DATA5~DATA7 stored in the backup block BU_B corresponding to the first page P3 and P5~P7. The second page P9, P11~P13 of a block B1 is as shown in part (D) of Fig. 5.

Figure 6 is a flow chart of an embodiment of a data maintenance method provided by the present invention. The data maintenance method is applicable to the data storage device of Figure 1. The flow begins in step S600.

In step S600, the data storage device 140 replies from a power down event. In detail, the power down event can be any event that causes the data storage device 140 to lose operating voltage and is unable to operate.

Next, in step S602, the controller 160 selects one of the first blocks to be written before the power-off event in the block that the flash memory 180 has. In other words, the controller 160 finds the last block to be written before the power down event in the block that the flash memory 180 has.

Next, in step S604, the controller 160 writes the data in the plurality of first pages in the first block to the other plurality of second pages outside the first page in the first block. In other words, in step S604, since the first block is the block that is being written when the power-off event occurs, the controller 160 will have the valid data originally in the first block (the first page of the data) ), write other pages (second page) that do not have valid data to prevent the data from being stored in unstable pages. The flow ends in step S604. It should be noted that in other embodiments, the foregoing embodiment of the backup block may be included in step S604, or an embodiment including redundant data writing may be included, and the present invention is not limited thereto.

Figure 7 is a flow chart of an embodiment of another data maintenance method provided by the present invention. The data maintenance method is applied to the data storage device 140 shown in FIG. The flow begins in step S700.

In step S700, the data storage device 140 replies from a power outage event. In detail, the power down event can be any event that causes the data storage device 140 to lose operating voltage and is unable to operate.

Next, in step S702, the controller 160 selects one of the first blocks to be written before the power-off event in the block that the flash memory 180 has. In other words, the controller 160 finds the last block to be written before the power down event in the block that the flash memory 180 has.

Next, in step S704, the controller 160 is on the page of the first block. The last page to be written before the power down event is selected as a reference page.

Next, in step S706, the controller 160 determines the first page according to the first word line in the word line for controlling one of the reference pages. In detail, the first page is a page having valid data in a plurality of third pages controlled by the first word line and the at least one second word line arranged in front of the first word line. In other words, the controller 160 selects, as the first page, a page having valid material in the plurality of third pages controlled by the first word line and the at least one second word line arranged in front of the first word line.

Next, in step S708, the controller 160 determines whether there is a backup of the first page in a backup block. When there is a backup of all the first pages in the backup block, the flow proceeds to step S710; otherwise, the flow proceeds to step S712.

Next, in step S710, the controller 160 writes the data in the first page in which the backup block does not have a backup to the backup block.

Next, in step S712, the controller 160 determines whether the plurality of third pages controlled by the first word line and the at least one second word line arranged in front of the first word line do not have valid data. When any of the third pages does not have valid materials, the flow proceeds to step S714; otherwise, the flow proceeds to step S716.

In step S714, the controller 160 writes dummy data to the page in the third page that does not have valid data to stabilize the first block.

Next, in step S716, the controller 160 writes the other plural second pages in the first block according to the data stored in the backup block corresponding to the first page to write the data of the first page into the first page. Two pages. In other words, control The controller 160 reads the data of the first page in the spare block, and writes the read data of the first page into other pages in the first block that do not have valid data (second page). The flow ends in step S716.

The data storage device and the data maintenance method provided by the present invention can rewrite potentially damaged data into the same block after a power failure event. In some embodiments, the data storage device and the data maintenance method may also make the effective data more stable by using the spare block and the surplus data.

The method of the invention, or a particular type or portion thereof, may exist in the form of a code. The code can be stored in a physical medium such as a floppy disk, a CD, a hard disk, or any other machine readable (such as computer readable) storage medium, or is not limited to an external form of computer program product, wherein When the code is loaded and executed by a machine, such as a computer, the machine becomes a device for participating in the present invention. The code can also be transmitted via some transmission medium, such as a wire or cable, fiber optics, or any transmission type, where the machine becomes part of the program when it is received, loaded, and executed by a machine, such as a computer. Invented device. When implemented in a general purpose processing unit, the code combination processing unit provides a unique means of operation similar to application specific logic.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent. In addition, any of the objects or advantages or features of the present invention are not required to be achieved by any embodiment or application of the invention. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention.

100‧‧‧Electronic system

120‧‧‧Host

140‧‧‧Data storage device

160‧‧‧ Controller

162‧‧‧ arithmetic unit

164‧‧‧Permanent memory

166‧‧‧ random access memory

180‧‧‧Flash memory

Claims (18)

A data storage device comprising: a flash memory, comprising a plurality of blocks, each of the blocks comprising a plurality of pages; and a controller, when the data storage device replies from a power outage event, Selecting, in the block, one of the first blocks to be written before the power-off event, and writing the data in the plurality of first pages in the first block to the first block The other plural second page outside the page. The data storage device of claim 1, wherein the first block further comprises a complex digital element line, and the first block is a second-order storage unit block (MLC block), wherein the first block Each of the word lines is used to control two of the pages in the first block. According to the data storage device of claim 2, wherein the controller is further configured to select the power-off event in the pages of the first block when the data storage device returns from the power-off event The last page that was previously written is used as a reference page, and the first page is determined based on the first word line in the word line for controlling one of the reference pages. The data storage device of claim 3, wherein the first page is a plurality of third words controlled by the first word line and at least one second word line arranged in front of the first word line A page with valid material on the page. The data storage device of claim 4, wherein the controller is further configured to write dummy data into pages of the third page that do not have valid data. According to the data storage device of claim 1, wherein the controller is further configured to determine whether a backup block has a backup of the first page, and the first page does not have the backup block in the first page. The backuper's data is written to the backup block. The data storage device of claim 6, wherein the controller is further configured to write the second pages according to the data stored in the backup block corresponding to the first pages to The first page of information is written to the second page. According to the data storage device of claim 6, wherein the backup block has higher data protection capability than the first block. The data storage device of claim 8, wherein the first block is a second-order storage unit block (MLC block), and the backup block is a single-stage storage unit block (SLC block). A data maintenance method is applicable to a data storage device having a flash memory, wherein the flash memory includes a plurality of blocks, each of the blocks includes a plurality of pages, and the data maintenance method includes: When the storage device replies from a power outage event, select one of the first blocks to be written in the block before the power down event; and the first page in the first block The data is written to other plural second pages outside the first page in the first block. According to the data maintenance method of claim 10, the first block further includes a complex digital element line, and the first block is a second-order storage unit block (MLC block), wherein the first block Each of the word lines is used Control two of the pages in the first block. According to the data maintenance method of claim 11, the method further includes: selecting, in the pages of the first block, the last page to be written before the power-off event as a reference page; The first word line in the word line for controlling one of the reference pages determines the first page. According to the data maintenance method of claim 12, wherein the first page is a plurality of third words controlled by the first word line and at least one second word line arranged in front of the first word line. A page with valid material on the page. According to the data maintenance method of claim 13 of the patent application scope, it further includes writing dummy data to pages of the third page that do not have valid data. According to the data maintenance method of claim 10, the method further includes: determining whether a backup block has a backup of the first page; and the first page has no backup data in the backup block. Write to this backup block. According to the data maintenance method of claim 15, wherein the information in the first page in the first block is written into the other second of the first block outside the first page. The step of the page further includes: writing the second pages according to the data stored in the backup block corresponding to the first pages to write the data of the first pages to the second pages. According to the data maintenance method of claim 15 of the patent application scope, wherein the backup area The data protection capability of the block is higher than that of the first block. According to the data maintenance method of claim 17, wherein the first block is a second-order storage unit block (MLC block), and the backup block is a single-stage storage unit block (SLC block).