TWI455135B - Flash-based storage device and data writing method for the same - Google Patents

Description

Flash memory-based storage device and data writing method thereof

The present invention relates to a data writing method, and more particularly to a data writing method for a flash memory-based storage device and a storage device using the same.

Nowadays, the use of flash memory has become more common and the amount of data that can be stored has gradually increased. The flash memory is an electrically erasable programmable read only memory (EEPROM). Unlike general electronic erasable programmable read-only memory, flash memory can delete a block at a time. The block size of the flash memory will vary with different types of flash memory devices. Flash memory devices are generally thin, light, and consume relatively low amounts of power. Therefore, flash memory is quite suitable for consumer electronics.

In general, flash memory-based storage devices, such as solid state disks (SSDs) or USB handy drives, use standard FAT (file allocation table) or NTFS (new). The file system of the technology file system is used for file access control. However, when a flash memory-based storage device is applied to an industrial computer (industrial PC), in some applications, it is necessary to prevent the data from being modified, or to keep a record of the important data. Therefore, there is a need to configure a controller that sets the flash memory-based storage device to limit the writing of each magnetic zone so that each magnetic zone can be written only once or written to a predetermined write. The number of times to prevent certain data from being overwritten or erased. The present invention has been made to address this need.

It is an object of the present invention to provide a flash memory-based storage device that can disable a block when it is to be written into a block of flash memory that has been written for a predetermined number of writes. Written by the data.

Another object of the present invention is to provide a data writing method for a flash memory-based storage device, which can be used when a data is to be written into a flash memory that has been written for a predetermined number of writes. When the block is blocked, the block is prohibited from being written by the data.

The flash memory-based storage device of the present invention mainly comprises a flash memory having a plurality of blocks, and a flash controller having a main comparison table and a plurality of secondary comparison tables, wherein each A secondary comparison table records an operation record of a block, and a data access control unit is configured to allow all blocks to be written by a predetermined number of writes via the secondary comparison table, and When the written block has been written to the predetermined number of writes, the block is prohibited from being written by the data.

In addition, the data writing method of the present invention is for a flash memory-based storage device, wherein the flash memory has a plurality of blocks and the storage device has a plurality of secondary look-up tables to record the An operational state of the block, wherein the secondary look-up table has a flag indicating whether the block can be written, the write method includes Column step: (I) determining whether the flag in the secondary record table of the block to which the data is to be written is in an active state, and (II) the flag in the secondary record table of the block to which the data is to be written. Not in the active state, the block is prohibited from being written by the data.

100‧‧‧Flash memory-based storage devices

102‧‧‧Flash controller

104‧‧‧Flash memory

1022‧‧‧ Random access memory

1022a‧‧‧ main comparison table

1022b‧‧‧ secondary comparison table

1024‧‧‧Control logic

1024a‧‧‧ Data Access Control Unit

202‧‧‧Logic block number

204‧‧‧Physical block number

206‧‧‧Write counter

208‧‧‧Write enable flag

The foregoing description, as well as other features and advantages of the present invention, will be best understood by System block diagram of an example; second diagram A shows a schematic diagram of a preferred embodiment of the main comparison table of the present invention; and second diagram B shows a schematic diagram of a preferred embodiment of the secondary comparison table of the present invention; The figure is a flow chart of the data writing method of the present invention.

The first figure shows a system block diagram of a preferred embodiment of a flash memory based storage device of the present invention. As shown in the first figure, the flash memory-based storage device 100, such as a solid state disk, includes a flash memory 104 and a flash controller 102. The flash memory 104 is composed of a plurality of blocks, each of which is generally 512 bytes in size. Each block is represented by a logical block addressing (LBA), and the index code of the logical block address is incremented with the number of the block. As shown in the second figure, the flash memory 104 includes N blocks, which are represented by LBA 0, LBA 1 ... LBA N . The flash controller 102 is used to control the data access of the flash memory 104, which includes a random access The memory (RAM) 1022 has a primary mapping table 1022a that records the relationship between the logical location of the flash memory 104 and the physical location, and a plurality of secondary mapping tables 1022b. , record the operation records (log) of all blocks (LBA 0, LBA 1, ..., LBA N). The flash controller 102 further includes a control logic 1024 having a data access control unit 1024a. The data access control unit 1024a asks the operator if there is data to be written or deleted. If there is data to be deleted, the data access control unit 1024a issues a data delete command to delete the data of all the blocks (LBA 0, LBA 1, ..., LBA N) of the flash memory 104. The data deletion command can be a Secure Erase command of the ATA command set or a data deletion command defined by the ATA command set. When there is data to be written to the block of the flash memory 104, the material access control unit 1024a reads the operation log (log) of the secondary lookup table 1022b to determine whether the block to be written can be written. If the operation record in the secondary look-up table of the block to be written indicates that the block cannot be written, the data access control unit 1024a prohibits the block from being written.

A second diagram A shows a schematic diagram of a preferred embodiment of the primary look-up table 1022a of the present invention. As shown in the second figure A, the main lookup table 1022a includes a logical block number 202 and a physical block numbering 204 for respectively recording the logical block number and the physical block number. Thereby, the logical block and the correspondence between the physical blocks are presented. A second diagram B shows a schematic diagram of a preferred embodiment of a secondary look-up table 1022b of the present invention. As shown in the second diagram B, the secondary lookup table 1022b includes a writing counter 206 and a writing enable flag 208, wherein the write counter 206 records the number of times the block was written. And write the enabling flag The flag 208 provides an indication of whether the block can be written. In this embodiment, if the number in the write counter 206 reaches a predetermined number of writes, for example, once, the data access control unit 1024a sets the write enable flag 208 of the block to be inactive. . For example, if the block LBA 0 has been written once, the data access control unit 1024a sets the write enable flag 208 of the block to 0 to indicate a stopped state, indicating that the block becomes unwritten. status. As described above, if the data is to be written to the block where the write enable flag 208 is stopped, for example, LBA 0, the data access control unit 1024a will prohibit the block from being written.

The third figure is a flow chart of the data writing method of the present invention. The data writing method of the present invention is applicable to a flash memory-based storage device, which will now be described. The program of the data writing method of the third figure begins in step 300, in which the write enable flag 208 of each block is initially set to an active state, that is, set to 1. Next, in step 302, it is determined whether there is data to be written to the flash memory 104 or the flash memory 104 whether the data is to be deleted. If the data of the flash memory 104 is to be deleted, the execution of the program jumps to step 306 to delete the data in all the blocks in the flash memory 104 and set the write enable flag of the secondary table of all the blocks. It is active, and then the execution of the program jumps to step 316 and ends. If there is data to be written to the flash memory 104, execution of the program jumps to step 304 to determine whether the write enable flag in the secondary lookup table of the block to be written is active. If not, the write enable flag in the secondary lookup table of the block to be written is inactive and not writable, and execution of the program jumps to step 314 to disable the flash memory 104. The block is written by the data, and then execution of the program jumps to step 316 to end. If so, the write enable is active for the secondary lookup table of the block to be written, and the execution of the program jumps to step 308 to write the data to the block to be written and The number of the write counter for this block is incremented by one. Next The execution of the program jumps to step 310 to determine if the number of write counters for the block has reached a predetermined number of writes. If not, execution of the program jumps to step 316 and ends. If so, execution of the program jumps to step 312 to set the write enable flag for the block to inactive, and then execution of the program jumps to step 316 to end.

In summary, the present invention discloses a data writing method for a flash memory-based storage device, which is characterized by permitting each block of the flash memory to be written for a predetermined number of writes. If the block to which the data is to be written has been written to the predetermined number of writes, the block is prohibited from being written by the data. In order to achieve the object, the present invention has a plurality of secondary comparison tables in the random access memory of the flash controller storing the memory, and each secondary comparison table records an operation record of a block, which is included for determining Whether the block can be written to the flag. In addition, the control logic of the flash controller has a data access control unit that reads the operation record of the block recorded by the secondary look-up table to determine whether the block can be written. If the flag indicates that the block cannot be written, the data access control unit 1024a prohibits the block from being written.

This case has been modified by people who are familiar with the technology, but it is not intended to be protected by the scope of the patent application.

Claims (10)

A flash memory-based storage device comprising: a flash memory having a plurality of blocks; and a flash controller having a main lookup table and a plurality of secondary comparison tables, wherein each A secondary comparison table records an operation record of a block, and a data access control unit is configured to allow all blocks to be written by a predetermined number of writes via the secondary comparison table, and When the written block has been written to the predetermined number of writes, the block is prohibited from being written by the data. A flash memory-based storage device as described in claim 1, wherein the block is represented by a logical block address. A flash memory-based storage device as described in claim 1, wherein the primary comparison table records the logical position of the blocks and the correspondence between the physical locations. The flash memory-based storage device of claim 1, wherein the secondary comparison table includes a counter that counts the number of writes of a block and indicates whether the block can be written. a flag. The flash memory-based storage device of claim 4, wherein the data access control unit is configured to: when a block has been written to the predetermined number of writes, the secondary A flag indicating whether the block can be written is stopped as indicated by the comparison table to indicate that the block cannot be written. A data writing method for a storage device based on a flash memory, wherein the flash memory has a plurality of blocks and the storage device has a plurality of secondary pairs The table is operative to record the operational status of the blocks, wherein the secondary look-up table has a flag indicating whether the block can be written, the writing method comprising the steps of: determining the block to which the data is to be written Whether the flag in the secondary record table is in the active state; and if the flag in the secondary record table of the block to which the data is to be written is not in the active state, the data is prohibited from being written into the block. The data writing method for a flash memory-based storage device according to claim 6, wherein the secondary comparison table further comprises a counter for counting the number of writes of a block. And the writing method comprises the following steps: if the flag in the secondary record table of the block to be written by the data is in an active state, the data is written into the block to be written and the number of the counter is incremented by one. . The data writing method for a flash memory-based storage device according to claim 6, further comprising the steps of: determining whether the counter number reaches a predetermined number of writes; The number of the counter reaches the predetermined number of writes, and the flag in the secondary record table is set to a stopped state. A data writing method for a flash memory-based storage device according to claim 6, wherein the flag in the secondary recording table of the block in which the data is to be written is determined to be Before the step of the state of the activity, the following steps are further included: determining whether there is data to be written or deleted; and if it is determined that there is data to be deleted, issuing a delete command to delete the contents of all the blocks. The data writing method for a flash memory-based storage device according to claim 9, wherein the delete command is a Secure Erase command in the ATA command set or a custom ATA command.