TWI712882B - Data storage device and control method for non-volatile memory - Google Patents

Abstract

High-efficiency control technology for non-volatile memory. A controller moves valid data from a first source block to an active block in batches and, between the different batches, write data from a host is allowed to be stored to the active block. In the absence of a second source block, the controller moves each batch with a first amount of data to the active block. On the contrary, the controller moves each batch with a second amount of data to the active block. The second amount of data is greater than the first amount of data, and such a design is intended to accelerate data movement of the first source block.

Description

Data storage device and non-volatile memory control method

This case is about the control of non-volatile memory.

Non-volatile memory has many forms-for example, flash memory (flash memory), magnetoresistive RAM (Magnetoresistive RAM), ferroelectric random access memory (Ferroelectric RAM), resistive random access Memory (Resistive RAM), Spin Transfer Torque-RAM (STT-RAM), etc., are used for long-term data storage and can be used as storage media to realize a data storage device.

Non-volatile memory usually has its special storage characteristics. The technical field needs to develop corresponding control technology corresponding to the storage characteristics of non-volatile memory.

A data storage device implemented according to an embodiment of this case includes a non-volatile memory and a controller. The controller operates the non-volatile memory according to the request of a host. The controller configures an active block from a plurality of idle blocks of the non-volatile memory to fill in the write data required by the host. The controller further uses the active block as a transfer destination of valid data of a first source block in the non-volatile memory. The controller moves the effective data of the first source block to the active block in a plurality of batches, and allows the write data requested by the host to be filled in the active block between different batches. When there is no second source block, the controller causes the batches that move the first source block to each move a first amount of data. When the second source block exists, the controller causes the batches that move the first source block to each move a second amount of data. The second data amount is higher than the first data amount.

In one embodiment, the controller increases the amount of second data when there is a third source block.

In one embodiment, the controller allows the valid data of the first source block to be completely moved to the active block before allowing the valid data of the second source block to be moved to the active block.

In one embodiment, the controller sets the amount of data to be moved by each of the batches of the first source block before moving the valid data of the first source block.

In one embodiment, the controller estimates a ratio x:(y-x) based on the number of effective pages x of the first source block and the number of idle pages y of the active block, which is equivalent to 1:n. The controller sets a value a according to the total number of source blocks. The controller sets the value a as a normal value when only the first source block exists, and sets the value a to be greater than the normal value when not only the first source block exists. The controller implements a batch of movement of the first source block and writing of the writing data requested by the host with a ratio a:n.

In one embodiment, the controller further sets a value M according to the programmed response time of the non-volatile memory. After the controller moves a*M pages of valid data from the first source block to the active block, it allows the n*M pages of write data requested by the host to fill in the active block.

In one embodiment, after the controller estimates the aforementioned values a*M and n*M, it first moves a*M pages of valid data to the active block, so as to allow the n*M pages of write data requested by the host to be filled into the Active block.

In one embodiment, the source block is selected because it should wait for the number of idle blocks to be less than a critical number, or find that the error correction fails, or perform preventive removal, or meet the loss average.

In one embodiment, after the controller moves all the valid data of the first source block to the active block, it releases the first source block as an idle block before the end writing of the active block is completed .

The operation of the above controller on the non-volatile memory can also be realized by other structures. This case can also realize the control method of non-volatile memory with the aforementioned concepts, including: operating a non-volatile memory according to the requirements of a host; configuring an active block from a plurality of idle blocks of the non-volatile memory and filling in the host The requested write data; the active block is used as the destination of the effective data of a first source block in the non-volatile memory; the effective data of the first source block is moved to the active block in multiple batches Block, and allow the write data requested by the host to be filled in the active block between different batches; when there is no second source block, the batches that move the first source block are moved by one A first amount of data; and when the second source block exists, the batches that move the first source block each move a second amount of data. The second data amount is higher than the first data amount.

Hereinafter, specific embodiments are given in conjunction with accompanying drawings to illustrate the content of the present invention in detail.

The following description lists various embodiments of the present invention. The following description introduces the basic concept of the present invention, and is not intended to limit the content of the present invention. The actual scope of invention shall be defined in accordance with the scope of patent application.

Non-volatile memory can be flash memory (Flash Memory), magnetoresistive RAM (Magnetoresistive RAM), ferroelectric random access memory (Ferroelectric RAM), resistive RAM (RRAM) ), Spin Transfer Torque-RAM (STT-RAM), etc., provide storage media for long-term data storage. The following discussion takes the flash memory as an example.

Nowadays, data storage devices often use flash memory as storage media to store user data from the host. There are many types of data storage devices, including memory cards (Memory Card), universal serial bus flash devices (USB Flash Device), solid state drives (SSD)... and other products. One application is to use multi-chip packaging to package flash memory and its controller together-called embedded flash memory modules (such as eMMC).

The data storage device using flash memory as the storage medium can be applied to a variety of electronic devices. The electronic devices include smart phones, wearable devices, tablet computers, virtual reality equipment, etc. The computing module of the electronic device can be regarded as a host, which operates the data storage device used to access the flash memory therein.

Data storage devices using flash memory as storage media can also be used to construct data centers. For example, the server can operate a solid state drive (SSD) array to form a data center. The server can be regarded as the host, operating the connected solid-state drive to access the flash memory.

FIG. 1 illustrates a data storage device 100 according to an embodiment of the present invention. The data storage device 100 includes a flash memory 102 and a controller 104. The host 106 indirectly accesses the flash memory 102 through the controller 104. In addition to receiving and executing write commands from the host 106, the controller 104 also actively moves the user data stored in the flash memory 102.

Flash memory has its special storage characteristics, which are described below.

The host 106 uses logical addresses (for example, logical block address LBA or global host page number GHP... etc.) to distinguish user data. The physical space of the flash memory 102 is divided into a plurality of blocks (Blocks) for allocation. Each block (Block) includes multiple pages (Pages). Each page includes N sectors (Sectors), N is an integer greater than one, such as: 4. A page of 16KB space can be divided into four sectors, each of which is 4KB. In one embodiment, a block is arranged to store data according to page numbers, from low to high numbers.

In one embodiment, the data storage device adopts multi-channel technology, which can virtualize multiple blocks of different channels into a super block, and multiple pages can be virtualized into a super page, and use super blocks and super pages to perform data Storage space management can speed up the data throughput of data storage devices.

The data storage device records the correspondence between the logical address and the physical address of the user data in a logical-physical address mapping table (Logical-Physical Mapping Table, L2P Table).

The storage space of the flash memory 102 needs to be erased before it can be used again, and the smallest unit of erase (Erase) is a block. Blocks can be divided into data blocks, active blocks and idle blocks. Idle blocks can be used as active blocks to write user data. When the active block is filled with user data, after closing processing (writing EOB (End of Block) information), the active block is changed to a data block. As user data is updated, some user data stored in the data block will be changed from valid data to invalid data. When the user data stored in the data block are all invalid data, it will be changed to an idle block after erasure. In another embodiment, a data block full of invalid data is changed to an idle block, and the erasing process is performed when the idle block becomes an active block.

The use of flash memory involves data movement procedures, which can be divided into garbage collection procedures and non-garbage collection procedures. When the number of free blocks is insufficient (for example, less than a critical number TH1), the storage space can be garbage collected (garbage collection) processing. For example, when multiple data blocks (also called source blocks) only store sporadic valid data, garbage collection can be performed and the valid data can be collected into one active block (also called destination block) to recover multiple data Block, increase the number of idle blocks.

There are many types of non-garbage collection programs, which are judged based on the endangered condition. For example, the data block (source block) where the error correction failure (ECC failed) is generated also needs to be moved to timely rescue the user data that can still be read. In addition, data blocks (source blocks) that are read too frequently also need to be moved to avoid user data damage caused by the reduction of the data storage capacity of the data block. This operation is also called preventive move (Early Move). In addition, data migration may also be initiated in response to wear leveling considerations between blocks, for example, all user data (including valid data and invalid data) in the data block (source block) with a low number of reads Move to the active block (destination block) with a higher erase count to recover the data block. In addition, the loss averaging process can also be combined with the garbage collection process, that is, the loss averaging process moves the valid data of multiple data blocks (source blocks) to the active block (destination block) with a higher erasure count.

It should be noted that the data transfer is preferably realized by data copying.

This case proposes a high-performance plan for the transfer of the above effective data. Once there is a need for data transfer, for example, the above garbage collection, error correction and failure removal, preventive removal, loss-average removal, or others, you can use this case removal technique.

In the figure, the idle blocks of the flash memory 102 belong to the idle block pool 108, and the data blocks belong to the data block pool 110. When the host 106 submits a write command or the controller 104 starts the data transfer procedure, the controller 104 selects an idle block from the idle block pool 108 as the active block A0. At this time, the idle area of the idle block pool 108 The number of blocks will be reduced by one. Afterwards, the user data is written into the active block A0. When the active block A0 is turned off and becomes a data block, the number of data blocks will increase by one.

Flash memory generally uses active block A0 to receive user data from the host. This user data is usually provided by a write command (see Host_Data for host write data path). In particular, instead of using another active block (called A1 to distinguish it from A0) to store user data from the source block, the controller 104 in this case makes the active block A0 also serve as the destination of the data transfer process, and Instead of using active block A1. Once there is a need for data movement, such as garbage collection, error correction invalidation movement, preventive movement, loss-average movement, or other, this case can collect user data from the source block in the data movement process to active block A0( (Refer to the data transfer path Blk_Data). . In particular, in this case, the effective data of the same block is divided into multiple batches and moved to the active block A0. This case is for different blocks, and the effective data volume of a single batch is set adaptively. The more data blocks generate effective data transfer requirements, the higher the amount of effective data transferred in a single batch. The amount of data provided to the active block A0 by the host write data path Host_Data and the data transfer path Blk_Data is dynamically allocated. It is discussed in more detail below.

Compared with the traditional technology where the active block A0 and the active block A1 are configured at the same time, the active block A0 in this case has several advantages, which are described as follows.

First of all, the active block A0 in this case can not only store user data requested by the host with a write command, but also store user data from the source block. Therefore, the usage of idle blocks can be reduced.

In the traditional example of using active block A1, in response to sudden power outages, the Sudden Power Off Recovery (SPOR) program must take special consideration of data reliability, and will discard the closed active Block A1 is still subject to the user data on the source block. Therefore, as long as the active block A1 is not closed, all source blocks in the data transfer process must be retained and cannot be released. The above design obviously drags down the recovery of source blocks, causing the number of idle blocks to not increase in time, and even leading to the start of different types of data transfer procedures.

Compared with the traditional technology, this case uses the active block A0 as the target block in the data transfer process. The SPOR procedure will not completely discard the active block A0. After the data transfer is completed, the source block in the data transfer process can be recovered, and there is no need to save it for the SPOR process. Therefore, compared with the traditional technology that specifically uses the active block A1 as the target block, the number of idle blocks in this case can be effectively increased to overcome the above-mentioned problems.

In addition, in order to close the active block A1 as the target block in the traditional technology, some dummy data may be filled in, which will reduce the data storage capacity of the data block and increase the erasure frequency of the block. , Shorten the life of flash memory. In contrast, using the active block A0 as the destination of the data transfer program can avoid the writing of false data and overcome the above-mentioned problems.

In one implementation, the controller 104 allows the valid data of a source block (whether garbage collection or non-garbage collection) to be completely moved to the active block A0 before allowing another source block (regardless of garbage collection or non-garbage collection). Valid data of garbage collection) is moved to the active block A0.

In this case, the effective data of the same source block is moved to the active block A0 in batches. Between each batch, the write data required by the host can be filled in the active block A0. There may be a proportional relationship between the effective data transfer and the filling of the written data from the host. This case adapts to set the proportional relationship. If there is more than one source block that requires data movement, this project increases the amount of effective data moved in a single batch and ends the effective data movement of the current source block as soon as possible to cope with the next source block.

In Figure 1, the write data requested by the host 106 is written to the data path Host_Data via the host. Garbage collection, error correction and failure migration, preventive migration, loss-average migration, etc., various valid data migrations with active block A0 as the destination are represented by the data migration path Blk_Data in Figure 1. Any data block selected from the data block pool 110 as the source block and the valid data is moved to the active block A0 belong to the technology covered by the data moving path Blk_Data. This case is to dynamically allocate the path Host_Data and the use of path Blk_Data.

In one implementation, the controller 104 allows other source blocks to also use the active block A0 as the effective data transfer destination after the previous source block is moved. For example, after the garbage collection of one source block is completed, the controller 104 allows another source block to use the same active block A0 as the destination for non-garbage collection (error correction failure removal, preventive removal, loss average removal, etc.) Etc.) effective data transfer. For example, after the effective data transfer of a source block that is not garbage collected is performed, the controller 104 allows another source block to use the same active block A0 as the destination to perform the effective data transfer that is not garbage collected again. In this way, before the active block A0 is closed (for example, based on whether the EOB information is completed as the criterion), the number of idle blocks has a chance to be fully replenished (more than one idle block can be added).

In one implementation, the valid data of the same source block is moved to the active block A0 in batches. In each batch, the write data required by the host 106 is filled in the active block A0. Or, between batches, the controller 104 makes the flash memory 102 respond to the read request of the host 106. The interval between different batches can be determined by the amount of data written in the host 106 of the active block A0 or defined by timing. There may be new and effective data transfer requirements between batches. The controller 104 will process the batch transfer of another source block after the batch transfer of the current source block is completed.

In one embodiment, the controller 104 estimates a ratio based on the effective data amount of a source block and the idle space of the active block A0, and sets the effective data amount for each batch transfer according to the ratio. According to the ratio, the controller 104 can further set the amount of data written by the host 106 to fill the active block A0 between two batches.

There may be more than one source block facing data movement needs. One embodiment dynamically allocates the above-mentioned ratio, sets the source block to be processed, and determines the effective amount of data transferred in each batch. In one implementation, there are two source blocks that require data movement. There are x pages of valid data in the first source block. The active block A0 has y pages of free space. In this case, a ratio of x:(y-x) can be estimated, which is equivalent to 1:n. In this case, the ratio can be adjusted to a:n, where a is a value greater than a normal value. For example, the normal value can be 1, and a can be 2. Considering the response time of flash memory 102 programming (including host 106 writing and source block transfer), the migration strategy developed in this project is: every a*M page of valid data is moved from the first source block to the active area Block A0 (corresponding to the path Blk_Data), that is, the active block A0 is interspersed to store the n*M page write data sent by the host 106 (corresponding to the path Host_Data). The multiple a enables the effective data of the first source block to be collected in the active block A0 early. The controller 104 can move the effective data of the second source block in time. The controller 104 will estimate a new ratio for the effective data amount of the second source block and the idle space of the active block A0 at this time. The controller 104 also confirms whether there are other source blocks to be moved, so as to adjust the ratio and generate a moving strategy suitable for the second source block.

In one embodiment, when the first source block sets the moving strategy, not only the second source block is waiting, but the third source block needs to be moved. The value of a can be set to be larger (compared to the example of only the first and second source blocks).

The response time of flash memory 102 programming (including host 106 writing and source block transfer) is affected by many factors. In this case, the reaction time is specially considered, and the aforementioned M value is set. In one embodiment, programming M pages at a time can optimize the write timing of the flash memory 102. For example, while waiting for the confirmation response of the first M-page programming, the second M-page can be cached to the controller 104 and waiting to be stored in the flash memory 102: the operating efficiency is much better than single-page programming.

In one embodiment, the controller 104 prioritizes the data transfer, and then considers the write request of the host 106. For example, once there is a source block for which data needs to be moved, the controller 104 performs the first batch of data movement after evaluating the movement strategy. After the transfer of the first batch of data is completed, the write data requested by the host 106 is allowed to be received again. This design ensures that the same source block is collected on the same active block A0.

FIG. 2 is a flowchart illustrating the data transfer performed on the flash memory 102 according to an embodiment of the present invention.

Step S202: The controller 104 configures the active block A0. The controller 104 allocates one of the idle blocks from the idle block pool 108 as the active block A0.

Step S204: The controller 104 judges whether to execute the data transfer procedure? If yes, execute step S212, if otherwise, execute step S206. When the preset conditions are met, for example, the number of idle blocks is less than the critical number TH1, or any one of error correction failure removal, preventive removal, and loss-average removal occurs, the controller 104 starts (executes) the data removal process.

Step S206: The controller 104 determines whether to close the active block A0? If yes, execute step S210, if otherwise, execute step S208. If the active block A0 still has free space to store data, the controller 104 does not close the active block A0.

Step S208: The controller 104 writes the user data from the host 106 into the active block A0, and then returns to step S204. In the above, the controller 104 executes step S204 first, and then steps S206 and steps S208/S210 are executed, which means that the controller 104 will preferentially move the user data of the data movement procedure. In another embodiment, the controller 104 can arrange step S204 after the user data of the host 106 is filled in; under this setting, the controller 104 will write the user data of the host 106 into the active block A0 first.

Step S210: The controller 104 closes the active block A0. If the active block A0 has no free space to store data, the controller 104 closes the active block A0 and writes EOB information into the last page of the active block A0.

If step S204 shows that there is a data transfer requirement, the process proceeds to step S212 to plan a source block's effective data transfer strategy. The controller 104 not only considers the effective data amount of the source block and the idle condition of the active block A0, but also considers whether there are more source blocks to be moved. The controller 104 thus evaluates a moving strategy. For example, every time a*M pages of valid data are moved, the host 106 inserts n*M pages to write data. Step S214 and step S216 are executed repeatedly to complete the moving strategy.

In step S214, the active block A0 is used as the destination to move the valid data of pages a*M of the source block. In step S216, the active block A0 restarts the reception of the write data sent by the host 106. The controller 104 allows the n*M pages of writing data required by the host 106 to fill in the active block A0. In step S218, the controller 104 determines whether the effective data transfer of the source block is completed. If not, the process returns to step S214 to continue the effective data transfer of the next batch of a*M pages. If step S218 determines that the effective data movement of the source block is completed, the flow proceeds to step S204 and subsequent steps to plan how to use the active block A0 space to meet another data movement demand.

In an implementation manner, step S216 may include a time limit judgment. When the time limit is exceeded, the flow proceeds to step S218.

FIG. 3 further describes step S212 in detail according to an embodiment of the present case, in which the number of data transfer pages a*M of each batch in step S214 and the number of pages written by the host 106 interspersed in step S216 are determined.

In step S302, the controller 104 estimates a ratio of 1:n based on the effective data amount of the source block and the idle space of the active block A0. For example, there are x pages of valid data in the source block. Active block A0 has y-page free space. According to step S302, the controller 104 estimates a ratio x:(y-x), which is equivalent to 1:n.

In step S304, the controller 104 determines whether there are a plurality of source blocks that require data movement. If not, the process goes to step S306. The controller 104 sets the value a to a normal value (for example, 1), indicating that there is no need to accelerate the movement. Conversely, if there are multiple source blocks that need to be moved, the process goes to step S308. The controller 104 makes the value a greater than the normal value (for example, 2) to accelerate the movement. The more source blocks wait for data to move, the larger the value a can be set.

The n value and the planned a value obtained by the program in Figure 3 are applied to steps S214 and S216 to determine the number of data transfer pages a*M for each batch and the host 106 writes allowed to be interleaved between each batch Number of incoming pages n*M.

The user's operating habits may cause the device to repeatedly power off and power on (called power cycling). For example, a mobile phone user opens the lid to view information and then closes the lid. A large amount of idle blocks are consumed, and garbage collection needs occur. Certain blocks may also be read too frequently, resulting in ECC failed movement, early move, wear leveling movement, or other effective data movement requests. This case allows the excessively low number of idle blocks to be filled in time.

The operation of the above controller 104 on the flash memory 102 can also be implemented by other structures. All the usage methods of the dynamic allocation of active block A0 (for example, the usage ratio of the dynamic allocation path Blk_Data and the path Host_Data) belong to the scope of protection of this case. In this case, the aforementioned concept can be used to realize the control method of non-volatile memory.

Although the present invention has been disclosed as above in the preferred embodiment, it is not intended to limit the present invention. Anyone familiar with the art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be subject to the scope of the attached patent application.

100: data storage device; 102: flash memory; 104: controller; 106: host; 108: idle block pool; 110: data block pool; A0: active block; Blk_Data: data migration path; Host_Data: The host writes the data path; S202...S218, S302...S308: Steps.

Fig. 1 illustrates a data storage device 100 according to an embodiment of the present case; Fig. 2 illustrates the data transfer performed on the flash memory 102 according to an embodiment of the present case in a flowchart; and Fig. 3 is more detailed according to an embodiment of the present case Step S208 is described, in which the number of data transfer pages a*M performed in each batch in step S210 is determined, and the number of pages written into the host 106 interspersed in step S212 is n*M.

100: Data storage device

102: flash memory

104: Controller

106: host

108: Idle block pool

110: Data block pool

A0: Active block

Blk_Data: data moving path

Host_Data: host write data path

Claims (16)

A data storage device includes: a non-volatile memory; and a controller for operating the non-volatile memory according to a host's request, wherein: the controller is configured from a plurality of idle blocks of the non-volatile memory The active block fills in the write data requested by the host; the controller further uses the active block as the transfer destination of the valid data of a first source block in the non-volatile memory; the controller moves in multiple batches The valid data of the first source block is sent to the active block, and the write data required by the host is allowed to fill the active block between different batches; when the controller does not have a second source block, The batches that move the first source block each move a first amount of data; when the second source block exists, the controller makes the batches that move the first source block each move a second Data amount; and the second data amount is higher than the first data amount. For the data storage device described in item 1 of the scope of patent application, wherein: the controller increases the amount of the second data when there is a third source block. Such as the data storage device described in item 1 of the scope of patent application, wherein: the controller allows the effective data of the first source block to be completely moved to the active block before allowing the effective data of the second source block to be moved To the active block. For example, the data storage device described in item 3 of the scope of patent application, wherein: the controller is set to move at the beginning of moving the valid data of the first source block The first data amount or the second data amount moved by the batches of the first source block. For the data storage device described in item 4 of the scope of patent application, wherein: the controller estimates a ratio x: (yx) based on the number of effective pages x of the first source block and the number of idle pages y of the active block, Equivalent to 1:n; the controller sets a value a according to the total number of source blocks; the controller sets the value a as a normal value when only the first source block exists, and when not only the first source block When the source block exists, the value a is set to be greater than the normal value; and the controller implements a batch of movement of the first source block and writing of the write data requested by the host with a ratio a:n. For the data storage device described in item 5 of the scope of patent application, wherein: the controller further sets a value M according to the programmed response time of the non-volatile memory; and the controller moves a* from the first source block After M pages of valid data are in the active block, n*M pages of write data requested by the host are allowed to fill in the active block. For example, the data storage device described in item 1 of the scope of patent application, among which: the source block is selected because it should wait for the number of idle blocks to be less than a critical number, or find that the error correction is invalid, or perform preventive removal, or meet Average loss. The data storage device described in item 1 of the scope of patent application, wherein: after the controller moves all the valid data of the first source block to the active block, it releases before the end of the active block is written The first source block is an idle block. A non-volatile memory control method, including: Operate a non-volatile memory according to the request of a host; configure an active block from a plurality of idle blocks of the non-volatile memory to fill in the write data requested by the host; and use the active block as the non-volatile memory The transfer destination of the valid data of a first source block in the body; move the valid data of the first source block to the active block in multiple batches, and allow the write data requested by the host between different batches Fill in the active block; when there is no second source block, the batches that move the first source block each move a first amount of data; and when the second source block exists, let The batches that move the first source block each move a second data amount, wherein the second data amount is higher than the first data amount. The non-volatile memory control method described in item 9 of the scope of the patent application further includes: when there is a third source block, increasing the amount of the second data. For example, the non-volatile memory control method described in item 9 of the scope of patent application further includes: after the valid data of the first source block is completely moved to the active block, the second source block is allowed to be valid The data is moved to the active block. For example, the non-volatile memory control method described in item 11 of the scope of patent application further includes: at the beginning of moving the valid data of the first source block, setting the first source block to move each of the above batches The first amount of data, or the second amount of data. Non-volatile memory control as described in item 12 of the scope of patent application The method further includes: estimating a ratio x: (yx) based on the number of effective pages x of the first source block and the number of idle pages y of the active block, which is equivalent to 1:n; according to the total number of source blocks Set a value a; when only the first source block exists, set the value a as a normal value, and when not only the first source block exists, set the value a to be greater than the normal value; and use a ratio a : N Implement a batch of movement of the first source block and write data requested by the host. The non-volatile memory control method described in item 13 of the scope of patent application further includes: setting a value M according to the programmed response time of the non-volatile memory; and moving a*M pages from the first source block After valid data arrives in the active block, the n*M page write data requested by the host is allowed to fill in the active block. For example, the non-volatile memory control method described in item 9 of the scope of patent application, in which: the source block is selected because it should wait until the number of idle blocks is less than a critical number, or the error correction is found to be invalid, or preventive Move, or meet the loss average. For example, the non-volatile memory control method described in item 9 of the scope of patent application further includes: after moving all the valid data of the first source block to the active block, before the end of the active block is written Release the first source block as an idle block.

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