WO2020037982A1

WO2020037982A1 - Data deleting method based on fat file, and data storage device and system

Info

Publication number: WO2020037982A1
Application number: PCT/CN2019/078404
Authority: WO
Inventors: 李虎; 梁永权
Original assignee: 深圳市德名利电子有限公司
Priority date: 2018-08-24
Filing date: 2019-03-16
Publication date: 2020-02-27
Also published as: CN109254953A

Abstract

A data deleting method based on an FAT file, and a data storage device and system. The method comprises: receiving a logical write command sent by a host (S101); determining whether an FAT file system is formatted (S102); if yes, setting an identifier as 1 (S103); after setting the identifier as 1 or determining that the FAT file system is not formatted, writing data according to the logical write command (S104); determining whether the storage device is in an idle state within a preset duration, and if yes, detecting whether the identifier is 1 (S105); if the identifier is 1, analyzing the FAT file system, counting invalid logical addresses, and deleting invalid logical mapping (S106); and setting the identifier as 0 (S107). The method can improve the writing speed of data and improve the service life of the data storage device.

Description

Data deletion method, data storage device and system based on FAT file

Technical field

The present invention relates to the technical field of data processing, and in particular, to a method, a data storage device, and a system for deleting data based on a FAT file.

Background technique

At present, data storage on many storage devices often uses FAT (File Allocation). Table (File Configuration Table) system for management. Referring to Figure 1, the FAT file system includes the system boot sector DBR, file allocation table FAT, and file directory table FDT. The system boot sector DBR records the system's starting sector and end Sector, file storage format, hard disk media descriptor, root directory size, FAT number, cluster size and other important parameters; file classification table FAT is used to record a linked list of pointers formed by the clusters occupied by each file. Each entry occupies two bytes, and each entry in FAT32 occupies 4 bytes. Each entry represents a family on the disk. The value of each entry is a pointer in a one-way chain. Generally, each partition has two identical entries FAT table; file directory table FDT records file name, starting FAT entry pointer, type, creation time, modification time, etc.

technical problem

During the use of existing storage devices, because the USB2.0 protocol does not support the logical erase data command, when the data in the storage device is no longer valid, the FAT file system format operation is usually used to delete the data. Modify the corresponding DBR, FAT, FDT and other tables, the data before the mark is invalid.

However, the format operation only deletes the file mapping relationship of the corresponding FAT file system, and does not delete the corresponding data. When the master of the storage device performs data management, the deleted file will still be considered to exist and new data will be written. During the process of recycling old data, the write speed becomes slower, and the service life of the storage device is reduced to a certain extent.

Technical solutions

Referring to FIG. 2, FIG. 2 shows a storage state in a NAND FLASH when a data storage device is full of data. There are 8 blocks in FLASH, each block contains 5 Pages, and LPX represents data in Logic Pages.

Referring to FIG. 3, FIG. 3 shows the storage status in the NAND FLASH after the data storage device is formatted by FAT. After formatting, the FAT table is updated, new data is written corresponding to LP1, LP2, and data corresponding to LP1 and LP2 on the block. Set to invalid, LP1, LP2 are system tables of FAT files, including DBR, FAT, FDT. After formatting, although LP3-LP30 is deleted in the FAT file system, it is not deleted in the logical mapping relationship of the storage device master. Therefore, the data is still considered valid on the NAND FLASH.

When new data needs to be written in the storage device, it is assumed that LP7-LP14 needs to be updated. Referring to FIG. 4, first write LP7, LP8, LP9 to Block7. Because there is only one empty block left, the effective data of Block1 and Block2 need to be recovered. Refer to Figure 5.

Referring to FIG. 6, after recovery, LP10, LP11, LP12, LP13, and LP14 are continuously written to Block1.

It can be seen from the process of writing new data that although only LP7 to LP14 are written, old data LP3, LP4, LP5, LP6, and LP10 need to be recovered.

Beneficial effect

An object of the present invention is to address the problems of slow data writing speed and short storage device life caused by storage device recycling of old data in the prior art, and to propose a data deletion method, data storage device, and system based on FAT files. Can effectively improve the speed of data writing and increase the life of storage devices.

A method for deleting data based on FAT files, including:

Receive the logical write command sent by the host;

Determine whether the FAT file system has been formatted;

If the FAT file system is formatted, set the flag to 1;

After setting the flag to 1, or after determining that the FAT file system has not been formatted, write data according to the logical write command;

Judging whether the storage device is in an idle state for a preset period of time, and if so, detecting whether the identifier is 1;

If the identifier is 1, analyze the FAT file system, count invalid logical addresses, and delete invalid logical mappings;

Set the flag to 0.

Further, determining whether the FAT file system has been formatted includes:

Determine whether the write logical address is 0;

If the write logical address is 0, it is determined that the FAT file system is formatted;

If the write logical address is non-zero, it is determined that the FAT file system is not formatted.

Further, determining whether the storage device is in an idle state includes:

Detecting whether the execution of the logical write command is completed within a preset time period;

If it is completed, it is detected whether a new logical write command is received, and if no new logical write command is received, it is determined that the storage device is in an idle state.

Further, analyzing the FAT file system, and counting invalid logical addresses, including:

Read the DBR table and the FAT table of the FAT file system, find invalid logical addresses according to the DBR table and the FAT table, and perform statistics.

A data storage device includes a main control unit and a NAND FLASH memory. The NAND The FLASH memory stores multiple instructions, and the main control unit is configured to read the instructions and execute:

Receive the logical write command sent by the host;

Determine whether the FAT file system has been formatted;

If the FAT file system is formatted, set the flag to 1;

Set the flag to 0.

Further, the main control unit is further configured to perform:

Determine whether the write logical address is 0;

Further, the main control unit is further configured to perform:

A data storage system includes the data storage device described above, and further includes a host, and the host is connected to the data storage device.

Further, the data storage device is a U disk or an SD card.

The FAT file-based data deletion method, data storage device and system provided by the present invention can distinguish the deleted file data, delete the deleted data in the logical mapping table controlled by the data storage device, and then write the new Data can effectively reduce the collection of old data and reduce NAND FLASH writes data, thereby increasing the speed of data writing and increasing the service life of data storage devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the data structure of the FAT file system.

FIG. 2 is a schematic diagram of full data in a data storage device.

FIG. 3 is a schematic diagram of a data storage device after FAT formatting.

FIG. 4 to FIG. 6 are schematic diagrams of the data structure of the updated data after the FAT formatting of the prior art data storage device.

FIG. 7 is a flowchart of an embodiment of a FAT file-based data deletion method according to the present invention.

FIG. 8 is a schematic structural diagram of an embodiment of a data storage device provided by the present invention.

FIG. 9 is a schematic structural diagram of an embodiment of a data storage system provided by the present invention.

10 to 11 are schematic diagrams of data structures in an application scenario in which data is deleted using the data deletion method provided by the present invention.

Best Mode of the Invention

Type the description of the preferred embodiment of the invention here.

Embodiments of the invention

In order to make the objectives, technical solutions, and effects of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

Example one

Referring to FIG. 7, this embodiment provides a method for deleting data based on a FAT file, including:

Step S101: Receive a logical write command sent by a host;

In step S102, it is determined whether the FAT file system has been formatted;

Step S103: if the FAT file system is formatted, set the flag to 1;

Step S104, after setting the flag to 1, or after determining that the FAT file system has not been formatted, write data according to the logical write command;

In step S105, it is determined whether the storage device is in an idle state for a preset period of time, and if so, it is detected whether the identifier is 1;

Step S106: if the identifier is 1, analyze the FAT file system, count invalid logical addresses, and delete invalid logical mappings;

In step S107, the identifier is set to 0.

Specifically, step S101 is executed to first establish a communication connection between the host and the data storage device, and the data storage device detects in real time whether a logical write command sent by the host is received.

Further, step S102 is executed to determine whether the FAT file system has been formatted after receiving the logical write command sent by the host, which specifically includes:

Determine whether the write logical address is 0;

For a FAT file, the address 0 is usually not written to the file. The address 0 is the DBR table address by default. It is only modified when formatting.

Step S103 is performed. If the FAT file system is formatted, the flag ERASE_FLR is set to 1 (Ture).

After performing step S104, after setting the flag to 1, or after determining that the FAT file system has not been formatted, write data according to the logical write command. After the data writing is completed, the logical write command execution is completed.

Further, step S105 is executed to determine whether the storage device is in an idle state for a preset period of time, which specifically includes:

As a preferred embodiment, the preset duration is 1 second.

If the storage device is in an idle state, check whether the flag is 1.

Step S106 is performed. If the identifier is 1, the FAT file system is analyzed, and the invalid logical addresses are counted, which specifically include:

Then delete the logical mapping corresponding to the invalid logical address.

After the deletion is completed, step S107 is executed to set the flag ERASE_FLR to 0 (FALSE).

The FAT file-based data deletion method provided in this embodiment can distinguish the file data that has been deleted, delete the deleted data in the logical mapping table controlled by the data storage device master, and write new data effectively. Reduce the recycling of old data, reduce NAND FLASH writes data, thereby increasing the speed of data writing and increasing the service life of data storage devices.

Example two

Referring to FIG. 8, this embodiment provides a data storage device including a main control unit 201 and a NAND FLASH memory 202. The NAND FLASH memory 202 stores a plurality of instructions. The main control unit 201 is configured to read the instructions and execute:

Receive the logical write command sent by the host;

Determine whether the FAT file system has been formatted;

If the FAT file system is formatted, set the flag to 1;

Set the flag to 0.

Specifically, first, the main control unit 201 establishes a communication connection with the host, and the main control unit 201 detects in real time whether a logical write command sent by the host is received.

Further, after receiving the logical write command sent by the host, the main control unit 201 is further configured to execute:

Determine whether the write logical address is 0;

Further, if the FAT file system is subjected to formatting processing, the main control unit 201 sets the flag ERASE_FLR to 1 (Ture).

After setting the flag to 1, or after determining that the FAT file system has not been formatted, the main control unit 201 sends a NAND to the NAND according to the logical write command. Data is written in the FLASH. After the data is written, the execution of the logic write command is completed.

Further, the main control unit 201 determines whether the storage device is in an idle state within a preset time period, and specifically includes:

Detecting whether the execution of the logical write command is completed;

If the storage device is in an idle state, the main control unit 201 detects whether the identification is 1.

Further, if the identifier is 1, the main control unit 201 is further configured to execute:

Then delete the logical mapping corresponding to the invalid logical address.

After the deletion is completed, the main control unit 201 sets the flag ERASE_FLR to 0 (FALSE).

The data storage device provided in this embodiment can distinguish the deleted file data, delete the deleted data in the logical mapping table controlled by the data storage device, and then write new data, which can effectively reduce the Recycling, reducing NAND FLASH writes data, thereby increasing the speed of data writing and increasing the service life of data storage devices.

Zh

Example three

Referring to FIG. 9, this embodiment provides a data storage system including a data storage device 301 and a host 302. The host 320 is connected to the data storage device 301.

For a specific working principle of the data storage device 301, refer to Embodiment 2, and details are not described herein again.

Data storage devices include, but are not limited to, data storage devices such as USB flash drives and SD cards based on the USB 2.0 protocol.

Zh

Embodiment 4

This embodiment provides a specific application scenario to further describe the FAT file-based data deletion method of the present invention.

Referring to FIG. 2 and FIG. 3, FIG. 2 shows that when the data storage device is full of data, the NAND Storage state in FLASH. There are 8 blocks in NAND FLASH, each block contains 5 Pages, and LPX represents data in Logic Page. Figure 3 shows the storage status in the NAND FLASH after the data storage device is formatted by FAT. After formatting, the FAT table is updated, new data is written to LP1 and LP2, and the data corresponding to LP1 and LP2 on the block is set to invalid. LP1 and LP2 are system tables of FAT files, including DBR, FAT, and FDT.

Further, referring to FIG. 10, after analyzing the FAT file system, it is found that the LP3-LP30 has been deleted, so the corresponding logical mapping is cleared. FIG. 10 shows the storage state of the NAND FLASH after the invalid logical mapping is cleared.

Figure 11 shows the process when the data storage device writes new data. Assume that LP7 to LP14 need to be updated now. Because there are many empty blocks at the moment, data can be written directly without recycling operations.

Zh

It should be understood that those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes should fall within the protection scope of the appended claims of the present invention.

Industrial applicability

Type an industrial usability description here.

Sequence Listing Free Content

Type the free description paragraph of the sequence list here.

Claims

A method for deleting data based on FAT files, which includes:

Receive the logical write command sent by the host;

Determine whether the FAT file system has been formatted;

If the FAT file system is formatted, set the flag to 1;

After setting the flag to 1, or after determining that the FAT file system has not been formatted, write data according to the logical write command;

Judging whether the storage device is in an idle state for a preset period of time, and if so, detecting whether the identifier is 1;

If the identifier is 1, analyze the FAT file system, count invalid logical addresses, and delete invalid logical mappings;

Set the flag to 0.
The method for deleting data based on a FAT file according to claim 1, wherein determining whether the FAT file system has been formatted comprises:

Determine whether the write logical address is 0;

If the write logical address is 0, it is determined that the FAT file system is formatted;

If the write logical address is non-zero, it is determined that the FAT file system is not formatted.
The method for deleting data based on a FAT file according to claim 1, wherein determining whether the storage device is in an idle state for a preset period of time, comprising:

Detecting whether the execution of the logical write command is completed within a preset time period;

If it is completed, it is detected whether a new logical write command is received, and if no new logical write command is received, it is determined that the storage device is in an idle state.
The method for deleting data based on a FAT file according to claim 1, characterized in that analyzing the FAT file system and counting invalid logical addresses comprises:

Read the DBR table and the FAT table of the FAT file system, find invalid logical addresses according to the DBR table and the FAT table, and perform statistics.
A data storage device, comprising a main control unit and a NAND FLASH memory, wherein the NAND FLASH memory stores a plurality of instructions, and the main control unit is configured to read the instructions and execute:

Receive the logical write command sent by the host;

Determine whether the FAT file system has been formatted;

If the FAT file system is formatted, set the flag to 1;

After setting the flag to 1, or after determining that the FAT file system has not been formatted, write data according to the logical write command;

Judging whether the storage device is in an idle state for a preset period of time, and if so, detecting whether the identifier is 1;

If the identifier is 1, analyze the FAT file system, count invalid logical addresses, and delete invalid logical mappings;

Set the flag to 0.
The data storage device according to claim 5, wherein the main control unit is further configured to:

Determine whether the write logical address is 0;

If the write logical address is 0, it is determined that the FAT file system is formatted;

If the write logical address is non-zero, it is determined that the FAT file system is not formatted.
The data storage device according to claim 5, wherein the main control unit is further configured to:

Detecting whether the execution of the logical write command is completed within a preset time period;

If it is completed, it is detected whether a new logical write command is received, and if no new logical write command is received, it is determined that the storage device is in an idle state.
The data storage device according to claim 5, wherein the main control unit is further configured to:

Read the DBR table and the FAT table of the FAT file system, find invalid logical addresses according to the DBR table and the FAT table, and perform statistics.
A data storage system, comprising the data storage device according to any one of claims 5 to 8, and further comprising a host, wherein the host is connected to the data storage device.
The data storage system according to claim 9, wherein the data storage device is a U disk or an SD card.