TWI497292B - A Method of Finding System Data Based on Index Block - Google Patents

Description

System data searching method based on index block

The invention relates to a system data searching method, in particular to a system data searching method based on an index block.

With the improvement of the memory system, in recent years, the application level of flash memory has become more and more extensive, and one of the most common ones is a flash memory storage device containing flash memory. In general, flash memory typically contains multiple memory blocks and a control chip. At least one of the memory blocks stores system data required for the flash memory storage device to be started, for example, a Logical to Physical Table (L2P Table), a block erase count ( Block Erase Count), and system management information such as the number of error pages (Invalid Page Count). During the startup of the flash memory storage device, the control chip must first find the location of the memory block storing the system data from the memory blocks to read from the corresponding memory block. The system data required for the flash memory storage device to start up, and then complete its startup procedure.

In addition, due to the innate structure, the flash memory has a limit on the number of times of erasing, that is, the number of erasures and the number of writes of the memory blocks are limited. In order to solve the above problem, the existing method is to use each of the memory blocks in a balanced manner by using Wear Leveling technology, instead of frequently fixing some memory blocks to prolong the use of flash memory. life.

However, for this reason, the control chip will not be an important system. The data is stored in a fixed memory block. In other words, each time the flash memory storage device startup program is executed, the control chip must spend a considerable amount of time to find the memory block storing the system data from all the memory blocks to complete the startup. The program is therefore not very efficient.

Accordingly, it is an object of the present invention to provide a method for finding a system data based on an index block.

Therefore, the system data searching method based on the index block of the present invention is applicable to a flash memory including a plurality of memory blocks and a control chip. The memory blocks include a primary index block, a primary index block, and a management block for storing system data. The index block-based system data searching method comprises the following steps: (A) the control chip searches for the main index block from the memory blocks; (B) after searching the main index block, the control chip And searching for the secondary index block according to a secondary index block address stored in the primary index block; (C) the control chip searching for the location according to a management block address stored in the secondary index block a management block; and (D) the control chip obtains system data from the management block.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Referring to FIG. 1 and FIG. 2, a preferred embodiment of the system for searching for system data based on an index block is applicable to a flash memory (not shown) including a plurality of memory blocks and a control chip. The memory blocks include a primary An index block, at least one index block to be indexed, and at least one management block storing system data. The primary index block includes a plurality of memory pages, and the memory pages include a primary index page that stores the secondary index block address. Moreover, the secondary index block also includes a plurality of memory pages, and the memory pages include a secondary index page storing a management block address. That is, the secondary index block address stored in the primary index page corresponds to the memory address of the secondary index block. The management block address stored in the secondary index page is the memory address corresponding to the management block. In addition, the system data stored in the management block includes a logical entity comparison table, the number of block erases, and the number of error pages. It is worth mentioning that the secondary index block storing the memory address of the management block is in an active state, so it can also be called a working secondary index block. Of course, if the index block does not store the memory address of the management block at a time, it is not a working secondary index block.

The index block based system data finding method will be further explained below.

As shown in step S01, the control chip searches for the main index block from the memory blocks. That is, the control chip sequentially determines from the memory blocks whether the currently searched memory block is the primary index block. If not, the search for the next memory block continues; if yes, proceed to step S02.

As shown in step S02, after the main index block is searched, the control chip searches the main index page from the memory pages of the main index block, and obtains the secondary index block from the main index page. Address. That is, only one of the memory pages of the main index block stores the secondary index block address. The memory page storing the address of the secondary index block is the main index page, so the main index page must be searched first.

It is worth mentioning that each memory page of the main index block has a time attribute, and the time point corresponding to the time attribute of the main index page is later than the time point corresponding to the time attribute of all other memory pages. In other words, the control chip can quickly search for the main index page from the memory pages according to the existing bi-search manner and according to the time attributes of the memory pages. Obtain the secondary index block address.

As shown in step S03, the control chip searches for the secondary index block according to the secondary index block address. Since the secondary index block address is the memory address of the secondary index block, the control chip can directly find the secondary index block according to the secondary index block address.

As shown in step S04, the control chip searches the secondary index page from the memory pages, and obtains the management block address from the secondary index page. That is, only one of the memory pages of the secondary index block stores the management block address. The memory page storing the management block address is the secondary index page, so the secondary index page must be searched first.

It is worth mentioning that, like the memory page of the primary index block, each memory page of the secondary index block also has the time attribute, and the time attribute corresponding to the time attribute of the secondary index page is late. All other The time point corresponding to the time attribute of the memory page. In other words, the control chip can also quickly search for the secondary index page from the memory pages according to the time attribute of the memory pages to obtain the management. Block address.

As shown in step S05, the control chip searches for the management block according to the management block address. Since the management block address is the memory address of the management block, the control chip can directly find the management block according to the management block address.

As shown in step S06, the control chip obtains system data from the management block to complete the startup process.

That is, unlike the existing mechanism, the control chip does not need to search for the management block one by one from all the memory blocks, and the memory blocks can be layered by the preferred embodiment. Dividing into the main index block, the secondary index block and the management block, the main index page can be quickly accessed only after searching the main index block in a part of the memory block. With the secondary index page, find the management block.

It is worth mentioning that the system data may need to be stored in other memory blocks due to special factors. For example, the original management block has been damaged, or it must be changed based on the existing wear leveling mechanism. The location of the deposit. The following steps will further describe the corresponding operations between the primary index block, the secondary index block, and the management block in the above case.

As shown in step S11, if it is necessary to select another memory block instead of the original management block to store the system data, step S12 is performed. that is, If the control chip determines that the system data needs to be stored in another memory block, then the main index block, the secondary index block, and the management block are selected from the memory blocks. The memory block acts as a new management block to replace the original management block.

As shown in step S12, it is determined whether the secondary index block has remaining space. Since the control chip has selected a new management block storage system data in step S11, the secondary index block must also correct the contents of its memory page. First, the control chip first determines whether the secondary index block has no remaining space, that is, whether all of its memory pages have stored data. If there is still space left, step S16 is performed; if there is no remaining space, step S13 is performed.

The secondary index block is erased as shown in step S13. Since all the memory pages of the secondary index block have stored data, but the management block address has to be updated, the secondary index block must be erased. Then, one of the memory pages is selected as the secondary index page to store the management block address corresponding to the new management block on the secondary index page.

As shown in step S14, it is determined whether the secondary index block has been corrupted. Since the number of times the control chip erases the secondary index block is too frequent, the secondary index block may be destroyed as a result. Therefore, if the control chip determines that the secondary index block is not damaged, the process returns to step S12; if the control chip determines that the secondary index block has been damaged, then step S15 is performed.

As shown in step S15, the secondary index block is changed and the main index page is updated. Since the secondary index block has been destroyed, the control crystal The slice must be different from the main index block, the secondary index block, and the memory block of the management block as a new secondary index block to replace the original Secondary index block.

Moreover, since the secondary index block has been changed, the secondary index block address originally stored in the main index page also needs to be changed. That is, the control chip must use the memory address of the new secondary index block as the secondary index block address and store it on the main index page.

Further, as mentioned above, if the control chip determines that there is still space left in the secondary index block, step S16 is performed.

The secondary index page is updated as shown in steps S16 and S17. That is, the secondary index page will use the memory address of the new management block as the management block address and store it on the secondary index page.

Therefore, under the existing wear leveling mechanism, even if the control chip frequently selects a new memory block as the management block for storing system data, the mechanism of the preferred embodiment can still be obtained efficiently. System information to complete the startup process.

In summary, based on the primary index block, the secondary index block, and the hierarchical relationship of the management block, system data can be efficiently found; if the location of the system data is frequently changed, By updating the main index page and the secondary index page, the system data can be efficiently found without affecting the startup program, so that the object of the present invention can be achieved.

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 Still It is within the scope of the patent of the present invention.

S01~S06‧‧‧Steps

S11~S17‧‧‧Steps

1 is a flow chart illustrating a preferred embodiment of a method for finding a system data based on an index block according to the present invention; and FIG. 2 is a flowchart illustrating an update management block, a secondary index page, and The process of the main index page.

S01~S06‧‧‧Steps

Claims (7)

An index data-based system data searching method is applicable to a flash memory comprising a plurality of memory blocks and a control chip, wherein the memory blocks comprise a main index block and a primary index block. And a management block for storing system data, the system data searching method based on the index block comprises the following steps: (A) the control chip searches for the main index block from the memory blocks; (B) when searching After the primary index block, the control chip further searches for the secondary index block according to a secondary index block address stored in the primary index block, where the primary index block includes a plurality of memory pages, The memory page includes a primary index page storing the secondary index block address, and step (B) includes the following sub-step (B-1): the control chip searches the primary index page from the memory pages, and Obtaining the secondary index block address from the primary index page, and (B-2) the control chip searching for the secondary index block according to the secondary index block address; (C) the control chip is stored according to a In the secondary index area The management block address of the block searches for the management block; and (D) the control chip obtains system data from the management block; wherein each memory page has a time attribute, and the time attribute of the main index page corresponds to The time point is later than the time point corresponding to the time attribute of all other memory pages. The index block-based system data searching method according to claim 1, further comprising a step (E) after the step (D): (E) the control chip is specified from the memory blocks The memory block of the primary index block, the secondary index block, and the management block is used as a new secondary index block to replace the original secondary index block. The index block-based system data searching method according to claim 2, further comprising a step (F) after the step (E): (F) the control chip is updated according to the new secondary index block The secondary index block address is stored, and the updated secondary index block address is stored on the main index page. According to the index block-based system data searching method of claim 1, the secondary index block includes a plurality of memory pages, and the memory pages include a secondary storage address of the management block address. Indexing page, and step (C) comprises the following sub-steps: (C-1) the control chip searches the secondary index page from the memory pages, and obtains the management block address from the secondary index page; C-2) The control chip searches for the management block according to the management block address. The index block-based system data searching method according to claim 4, wherein each memory page has a time attribute, and the time attribute of the secondary index page corresponds to a time point later than all other memories. The time point corresponding to the time attribute of the page. Index block-based system resources as described in item 5 of the scope of the patent application The method for finding a material further includes a step (G) after the step (D): (G) the control chip is different from the main index block and the secondary index block from the memory blocks. And the memory block of the management block is used as a new management block to replace the original management block. The index block-based system data searching method according to claim 6 further includes a step (H) after the step (G): (H) the control chip updates the management according to the new management block The block address, and the updated management block address is stored in the secondary index page.