Data recovery processing method, system and computer device based on solid state disk

Abstract

The application relates to a data recovery processing method and system based on a solid state disk, computer equipment and a storage medium, wherein the method comprises the following steps: a solid state disk works in a TRIM ignoring mode after obtaining a TRIM ignoring command issued by a host; when a user deletes a file, a file system marks an LBA interval associated with the deleted file in a data area as an unallocated data area; when the host issues a TRIM command, the solid state disk does not process the TRIM command, does not recycle a physical address where user data is stored, and replies to the host that the command is completed; when the file needs to be recovered, a converted LPA mapping relationship of the LBA interval corresponding to the deleted file still exists, and the physical address where the corresponding data is stored has not been recycled, and the host can normally access the corresponding data. The application realizes data rollback when a user mistakenly deletes a file, and supports user data recovery.

Description

Technical Field

[0001] This invention relates to the field of solid-state drive (SSD) technology, and in particular to a data recovery processing method, system, computer device, and storage medium based on SSDs. Background Technology

[0002] With the development of solid-state drive (SSD) technology, SSDs have been widely used in various applications and have gradually replaced traditional HDDs in the PC market, providing users with a better experience in terms of reliability and performance.

[0003] NAND flash memory operations have specific constraints. Once a physical address is written, it must be erased before it can be written again. Therefore, for writing host data, SSDs internally use an append-only approach, writing records sequentially to different physical addresses, and using a logical-to-physical mapping table to track the physical location of the latest logical data on the host. Furthermore, in the host's file system, when a file is deleted, a corresponding command (TRIM) is sent to the SSD. The SSD then reclaims the physical address corresponding to the logical address, erases it, and continues to use it. In some scenarios, when a user accidentally deletes a file, data rollback is required. Supporting this type of user data recovery is quite challenging for existing storage systems.

[0004] Currently, in existing SSDs, when the host deletes a file, it sends a TRIM command to the SSD, which carries the relevant logical address space. After receiving the command, the SSD reclaims the physical address pointed to by the corresponding logical address, erases it, and reuses it. However, in some scenarios, if a user accidentally deletes a file and needs to recover it, it cannot be done because the SSD's internal mappings and physical blocks have been destroyed. Summary of the Invention

[0005] Therefore, it is necessary to provide a data recovery processing method, system, computer equipment, and storage medium based on solid-state drives to address the aforementioned technical problems.

[0006] A data recovery processing method based on solid-state drives, the method comprising:

[0007] After receiving the TRIM ignore command from the host, the solid-state drive operates in TRIM ignore mode;

[0008] When a user deletes a file, the file system marks the LBA range associated with the deleted file in the data area as an unallocated data area;

[0009] When the host issues a TRIM command, the solid state disk does not process the TRIM command, does not recycle the physical address where the corresponding user data is stored, and replies to the host command completion;

[0010] When the deleted file needs to be recovered, the converted LPA mapping relationship of the LBA interval corresponding to the deleted file still exists, and the physical address where the corresponding data is stored has not been recycled, and the host can normally access the corresponding data.

[0011] In one of the embodiments, the method further comprises:

[0012] The host marks the corresponding data area as allocated by recovering the associated LBA interval of the deleted file in the file recovery partition;

[0013] The user normally operates the deleted file through the file system to realize the data recovery function.

[0014] In one of the embodiments, the method further comprises:

[0015] The solid state disk works in the TRIM enabled mode after obtaining the TRIM enable command issued by the host;

[0016] The host scans the file system, scans and collects the LBA interval corresponding to all unallocated data areas;

[0017] The host issues a TRIM command to the solid state disk, and the TRIM command describes the LBA interval corresponding to the collected unallocated data area.

[0018] In one of the embodiments, after the host issues a TRIM command to the solid state disk, the TRIM command describes the LBA interval corresponding to the collected unallocated data area, the method further comprises:

[0019] The solid state disk obtains the TRIM command issued by the host and converts the LBA to LPA;

[0020] For the LPA trimmed, the value in the corresponding table item is modified to a special value, indicating no valid data;

[0021] Recycle the corresponding physical address, and reply to the host to complete the TRIM command.

[0022] A data recovery processing system based on a solid state disk, the data recovery processing system based on a solid state disk comprises:

[0023] The first acquisition module is configured to cause the solid state disk to work in the TRIM ignore mode after obtaining the TRIM ignore command issued by the host;

[0024] A marking module is configured to mark the LBA interval associated with the deleted file in the data area as unallocated data area when the user deletes the file;

[0025] A first processing module is configured to, when the host issues a TRIM command, not process the TRIM command, not recycle the physical address where the corresponding user data is stored, and reply to the host that the command is completed;

[0026] A data recovery module is configured to, when the file needs to be recovered, the LPA mapping relationship converted from the LBA interval of the deleted file still exists and the physical address where the corresponding data is stored has not been recycled, and the host can normally access the corresponding data.

[0027] In one embodiment, the data recovery module is further configured to:

[0028] The host marks the corresponding data area as allocated by recovering the associated LBA interval of the deleted file in the file partition.

[0029] The user normally operates the deleted file through the file system to realize the function of data recovery.

[0030] In one embodiment, the system further comprises:

[0031] A second acquisition module is configured to, after the solid state disk acquires the TRIM enable command issued by the host, work in the TRIM enable mode.

[0032] A scanning module is configured to, when the host scans the file system, scan and collect the LBA interval corresponding to all unallocated data areas.

[0033] A command issuing module is configured to, when the host issues a TRIM command to the solid state disk, describe the LBA interval corresponding to the collected unallocated data area in the TRIM command.

[0034] In one embodiment, the system further comprises a second processing module configured to:

[0035] The solid state disk acquires the TRIM command issued by the host and converts the LBA to LPA.

[0036] For the LPA trimmed, the value in the corresponding table item is modified to a special value, indicating that there is no valid data.

[0037] Recycle the corresponding physical address and reply to the host that the TRIM command is completed.

[0038] A computer device comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any one of the above methods when executing the computer program.

[0039] A computer readable storage medium, having a computer program stored thereon, wherein the computer program implements the steps of any one of the above methods when executed by a processor.

[0040] The data recovery processing method and system based on the solid state disk, the computer device and the storage medium, by obtaining the TRIM ignore command issued by the host, work in the TRIM ignore mode; when the user deletes the file, the file system marks the LBA interval associated with the deleted file in the data area as an unallocated data area; when the host issues the TRIM command, the solid state disk does not process the TRIM command, does not recycle the physical address where the corresponding user data is stored, and replies to the host command completion; when the file needs to be recovered, the LPA mapping relationship converted by the LBA interval corresponding to the deleted file still exists, and the physical address where the corresponding data is stored has not been recycled, and the host can normally access the corresponding data. In the application, the host instructs the SSD to enter the TRIM ignore mode through a specific command, in the TRIM ignore mode, the SSD does not execute the TRIM command, and thus the physical block where the user data is stored is not recycled, when the host needs to recover the file, since the corresponding user data still exists, only the file allocation table information needs to be recovered. When the user mistakenly deletes the file, data rollback can be performed, and user data recovery is supported. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 It is a schematic diagram of a typical host file system;

[0042] Figure 2 It is a schematic diagram of the existing host file deletion process;

[0043] Figure 3 It is a flowchart of the data recovery processing method based on the solid state disk in one embodiment;

[0044] Figure 4 It is a flowchart of the data recovery processing method based on the solid state disk in another embodiment;

[0045] Figure 5 It is a schematic diagram of the implementation scheme of the data rollback in the application;

[0046] Figure 6 It is a schematic diagram of the implementation scheme of the complete deletion of user data in the application;

[0047] Figure 7A structural block diagram of a data recovery processing system based on a solid state disk in one embodiment;

[0048] Figure 8 A structural block diagram of a data recovery processing system based on a solid state disk in another embodiment;

[0049] Figure 9 A structural block diagram of a data recovery processing system based on a solid state disk in still another embodiment;

[0050] Figure 10 An internal structural diagram of a computer device in one embodiment. DETAILED DESCRIPTION

[0051] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application 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 application and do not limit the present application.

[0052] Reference Figure 1 A schematic diagram of a typical host file system. Specifically, a disk partition includes at least two regions: a file partition and a data region. The file partition allocates a certain structure for each file, which describes the associated information of the file: file name, attribute, timestamp, and associated data region information (LBA interval). The data region is divided into two types: a data region that has been allocated to a specific file and stores the content of the file; and a data region that is not allocated to any existing file and does not contain valid data.

[0053] By listing the file structure in the file partition, the allocated data region information (LBA interval) of the file can be found, and read and write access can be performed thereon. Further, if the file space grows, the data region currently marked as unallocated can be continuously allocated to the file for storage.

[0054] Reference Figure 2 As shown, when a user deletes a file on the host side, the conventional method of the existing SSD specifically includes the following steps:

[0055] S0: The user deletes a file (taking file 1 as an example), and the file system marks the LBA interval (file 1-data region 1, file 1-data 2) associated with the data region of file 1 as an unallocated data region for subsequent use by other files.

[0056] S1: The host issues a TRIM command and describes the LBA interval (file 1-data region 1, file 1-data 2) of the deleted file. LBA stands for Logical Block Address.

[0057] S2: The SSD internally converts the LBA to LPA, with each continuous 8 LBAs forming one LPA. For example, LBAs 0-7 correspond to LPA 0; LBAs 8-15 correspond to LPA 1, and so on.

[0058] S3: For the LPA (e.g., LPA X / Y in the figure) that is trimmed, the value in the corresponding table entry is modified to a special value (SSD self-defined, for example, 0xFFFFFFFF), representing no valid data.

[0059] S4: The corresponding physical address (e.g., GPPA X / Y in the figure) is recycled for subsequent writing.

[0060] S5: The host is replied to complete.

[0061] Under this scheme, the mapping information corresponding to the file deleted at the disk end is lost, and the corresponding physical address is recycled for reuse, so that even if the user wants to recover the file later, it cannot be achieved.

[0062] In one embodiment, as shown in Figure 3 a solid state disk-based data recovery processing method is provided, which comprises:

[0063] Step 302, after the solid state disk obtains the TRIM ignore command issued by the host, it works in the TRIM ignore mode;

[0064] Step 304, when the user deletes a file, the file system marks the LBA interval associated with the deleted file in the data area as an unallocated data area;

[0065] Step 306, when the host issues a TRIM command, the solid state disk does not process the TRIM command, does not recycle the physical address where the user data is stored, and replies to the host that the command is complete;

[0066] Step 308, when the file needs to be recovered, the LBA interval corresponding to the deleted file still exists after conversion, and the physical address where the corresponding data is stored has not been recycled, and the host can normally access the corresponding data.

[0067] In this embodiment, a solid state disk-based data recovery processing method is provided. Specifically, at the moment when the host is running, a specific command is used to instruct the SSD to enter the TRIM ignore mode. In the TRIM ignore mode, the SSD does not execute the TRIM command, and thus the physical block storing the user data is not recycled. When the host needs to recover the file, since the corresponding user data still exists, it is only necessary to recover the file allocation table information.

[0068] In one embodiment, the method further comprises: the host recovering the associated LBA interval of the deleted file in the file partition, and marking the corresponding data area as allocated; and the user normally operating the deleted file through the file system to realize the data recovery function.

[0069] Specifically, referring to the schematic diagram of the data-rollback-enabled implementation scheme shown in the figure, the specific implementation steps are as follows: Figure 5

[0070] S0: The host issues a TRIM ignore command to the SSD. After receiving the command, the SSD works in the TRIM ignore mode and does not process the TRIM command.

[0071] S1: The user deletes a file (taking file 1 as an example). The file system marks the LBA interval (file 1-data area 1, file 1-data area 2) associated with file 1 in the data area as unallocated data area for subsequent use by other files.

[0072] S2: The host issues a TRIM command and describes the LBA interval (file 1-data area 1, file 1-data area 2) of the deleted file.

[0073] S3: The SSD does not process the TRIM command and does not recycle the physical address where the corresponding user data is stored.

[0074] S4: The host is replied that the command is completed.

[0075] S5: The user intends to recover the file (file 1).

[0076] At this time, the LBA interval corresponding to file 1 still exists in the mapping relationship converted from the LPA, and the physical address where the corresponding data is stored has not been recycled, so the host can normally access the corresponding data.

[0077] Therefore, the host only needs to recover the structure body information (associated LBA interval) of file 1 in the file partition, and mark the corresponding data area "file 1-data area 1" and "file 1-data area 2" as allocated. Thereafter, the user can normally operate file 1 through the file system, thereby realizing the data recovery function.

[0078] ​In the above embodiment, the TRIM ignore mode is worked by acquiring the TRIM ignore command issued by the host; when the user deletes a file, the file system marks the LBA interval associated with the deleted file in the data area as unallocated data area; when the host issues the TRIM command, the solid state disk does not process the TRIM command, does not recycle the physical address where the corresponding user data is stored, and replies to the host command completion; when the file needs to be restored, the LPA mapping relationship converted by the LBA interval corresponding to the deleted file still exists, and the physical address where the corresponding data is stored has not been recycled, and the host can normally access the corresponding data. In the scheme, the host instructs the SSD to enter the TRIM ignore mode through a specific command, in the TRIM ignore mode, the SSD does not execute the TRIM command, and thus the physical block where the user data is stored is not recycled, when the host needs to restore the file, since the corresponding user data still exists, only the file allocation table information needs to be restored. When the user mistakenly deletes the file, data rollback can be performed, and user data recovery is supported.

[0079] In one embodiment, as shown in Figure 4 A solid state disk-based data recovery processing method is provided, and the method further includes:

[0080] Step 402, the solid state disk works in the TRIM enable mode after acquiring the TRIM enable command issued by the host;

[0081] Step 404, the host scans the file system, scans and collects the LBA interval corresponding to all unallocated data areas;

[0082] Step 406, the host issues the TRIM command to the solid state disk, and the LBA interval corresponding to the collected unallocated data area is described in the TRIM command;

[0083] Step 408, the solid state disk acquires the TRIM command issued by the host, and converts the LBA into LPA;

[0084] Step 410, for the LPA trimmed, the value in the corresponding table item is modified to a special value, indicating that there is no valid data;

[0085] Step 412, recycle the corresponding physical address, and reply to the host that the TRIM command is completed.

[0086] Specifically, referring to the complete deletion of corresponding user data process shown in Figure 6 For example, when the disk available space is not enough, the process specifically includes the following steps:

[0087] S0: the host issues the TRIM enable command, and the SSD works in the TRIM enable mode after receiving the command.

[0088] S1: The host scans the file system, scans and collects all unallocated data area corresponding LBA interval.

[0089] S2: The host issues a TRIM command, which contains data description of the collected unallocated data area corresponding LBA interval.

[0090] S3: The SSD internally converts LBA to LPA (for example, LBA 0-7 corresponds to LPA 0; LBA 8-15 corresponds to LPA 1, and so on).

[0091] S4: For the LPA (for example, LPA X / Y in the figure) that is trimmed, the value in the corresponding table entry is modified to a special value (SSD-defined, for example, 0xFFFFFFFF), indicating no valid data.

[0092] S5: Recycle the corresponding physical address (for example, GPPA X / Y in the figure) for subsequent writing.

[0093] S6: Reply to the host for completion.

[0094] In this embodiment, by using the TRIM ignore and enable commands, the SSD can work in different modes, and different processing is performed for the TRIM command to meet the needs of different scenarios:

[0095] 1) To prevent user from mistakenly deleting files, the SSD works in TRIM ignore mode, and the mapping and user data on the SSD are not actually destroyed. When the user needs to recover the file, only the file partition information needs to be modified in the host file system.

[0096] 2) When the disk space is insufficient, the SSD works in TRIM enable mode, at which time the host scans the file system, collects unallocated data area information, and constructs a corresponding TRIM command to the SSD, thereby triggering the SSD to recycle the corresponding physical block and release the space.

[0097] It should be understood that although Figures 3-6 the steps in the flowchart are shown in sequence according to the arrows, these steps are not necessarily executed in sequence according to the arrows. Unless otherwise specified in this article, the execution of these steps has no strict sequence restriction, and these steps can be executed in other orders. Moreover, Figures 3-6 at least part of the steps in may include multiple sub-steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily sequential, but can be executed in rotation or alternation with other steps or sub-steps or stages of other steps.

[0098] In one embodiment, as shown in Figure 7 A data recovery processing system 700 based on a solid state disk is provided, which comprises:

[0099] A first obtaining module 701 is configured to make the solid state disk work in a TRIM ignoring mode after obtaining a TRIM ignoring command issued by a host;

[0100] A marking module 702 is configured to mark a LBA interval associated with a deleted file in a data area as an unallocated data area when the user deletes the file;

[0101] A first processing module 703 is configured to make the solid state disk not process a TRIM command and not recycle a physical address where user data is stored and reply to the host that the command is completed when the host issues the TRIM command;

[0102] A data recovery module 704 is configured to make the LPA mapping relationship converted from the LBA interval of the deleted file still exist and the physical address where the corresponding data is stored not be recycled when the file needs to be recovered, so that the host can normally access the corresponding data.

[0103] In one embodiment, the data recovery module 704 is further configured to:

[0104] The host marks the corresponding data area as allocated by recovering the LBA interval associated with the deleted file in the file partition;

[0105] The user normally operates the deleted file through the file system to realize the function of data recovery.

[0106] In one embodiment, as shown in Figure 8 A data recovery processing system 700 based on a solid state disk is provided, which further comprises:

[0107] A second obtaining module 705 is configured to make the solid state disk work in a TRIM enabling mode after obtaining a TRIM enabling command issued by a host;

[0108] A scanning module 706 is configured to scan the file system by the host, scan and collect LBA intervals corresponding to all unallocated data areas;

[0109] A command issuing module 707 is configured to issue a TRIM command to the solid state disk by the host, wherein the TRIM command describes the LBA intervals corresponding to the unallocated data areas collected.

[0110] In one embodiment, as shown in Figure 9 A data recovery processing system 700 based on a solid state disk is provided, which further comprises a second processing module 708 configured to:

[0111] The solid state disk obtains the TRIM command issued by the host and converts the LBA into LPA;

[0112] For the LPA trimmed, the value in the corresponding table entry is modified into a special value, representing no valid data;

[0113] The corresponding physical address is recycled, and the host is replied that the TRIM command is completed.

[0114] The specific limitations of the solid state disk-based data recovery processing system can refer to the limitations of the solid state disk-based data recovery processing method in the foregoing, which will not be repeated here.

[0115] In one embodiment, a computer device is provided, and an internal structure diagram thereof can be as shown in Figure 10 The computer device includes a processor, a memory, and a network interface connected through a system bus. The processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for running the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is configured to communicate with an external terminal through a network connection. The computer program is executed by the processor to implement a solid state disk-based data recovery processing method.

[0116] Those skilled in the art can understand that Figure 10 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0117] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor executes the computer program to implement the steps in each of the above method embodiments.

[0118] In one embodiment, a computer readable storage medium is provided, and the computer readable storage medium stores a computer program. The computer program is executed by the processor to implement the steps in each of the above method embodiments.

[0119] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when the computer program is executed, the processes of the above-mentioned embodiments of the methods can be included. Any reference to memory, storage, databases, or other media in the embodiments provided by the present application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0120] The technical features of the above embodiments can be combined in any way. In order to make the description simple, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not exist, they should be considered as the scope of the present application.

[0121] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, some modifications and improvements can be made, which are all within the scope of the present application. Therefore, the scope of the patent of the present application should be subject to the appended claims.

Claims

1. A data recovery processing method based on a solid-state drive, the method comprising: After receiving the TRIM ignore command from the host, the solid-state drive operates in TRIM ignore mode; When a user deletes a file, the file system marks the LBA range associated with the deleted file in the data area as an unallocated data area; When the host issues a TRIM command, the solid-state drive does not process the TRIM command, does not reclaim the physical address where the corresponding user data is stored, and replies to the host that the command is complete. When the file needs to be recovered, the LPA mapping relationship after the LBA range corresponding to the deleted file still exists and the physical address where the corresponding data is stored has not been reclaimed, so the host can access the corresponding data normally. The method further includes: The host recovers the LBA range associated with the deleted files in the file partition and marks the corresponding data area as allocated; This allows users to recover deleted files through normal file system operations. The method further includes: After receiving the TRIM enable command from the host, the solid-state drive operates in TRIM enabled mode. The host scans the file system, scanning and collecting the LBA ranges corresponding to all unallocated data areas; The host sends a TRIM command to the solid-state drive, wherein the TRIM command describes the LBA interval corresponding to the unallocated data area collected; The step of sending a TRIM command from the host to the solid-state drive, wherein the TRIM command describes the LBA interval corresponding to the collected unallocated data area, further includes: The solid-state drive (SSD) receives the TRIM command from the host and converts the LBA to LPA. For LPAs that have been TRIM'd, modify the values ​​in the corresponding entries to special values ​​to indicate that there is no valid data; Reclaim the corresponding physical address and reply to the host to complete the TRIM command.

2. A data recovery processing system based on a solid-state drive, characterized in that, The solid-state drive-based data recovery processing system includes: The first acquisition module is used for the solid-state drive to acquire the TRIM ignore command issued by the host and then work in TRIM ignore mode; The marking module is used by the file system to mark the LBA interval associated with the deleted file in the data area as an unallocated data area when a user deletes a file; The first processing module is used when the host issues a TRIM command. The solid-state drive does not process the TRIM command, does not reclaim the physical address where the corresponding user data is stored, and replies to the host to complete the command. The data recovery module is used when a file needs to be recovered, provided that the LPA mapping relationship after the LBA range corresponding to the deleted file is still present and the physical address where the corresponding data is stored has not been reclaimed, and the host can access the corresponding data normally. The data recovery module is also used for: The host recovers the LBA range associated with the deleted files in the file partition and marks the corresponding data area as allocated; This allows users to recover deleted files through normal file system operations. The system also includes: The second acquisition module is used for the solid-state drive to obtain the TRIM enable command issued by the host and then work in the TRIM enable mode. The scanning module is used by the host to scan the file system, scan and collect the LBA intervals corresponding to all unallocated data areas; The command issuing module is used by the host to issue a TRIM command to the solid-state drive. The TRIM command describes the LBA interval corresponding to the collected unallocated data area. The system further includes a second processing module, the second processing module being used for: The solid-state drive (SSD) receives the TRIM command from the host and converts the LBA to LPA. For LPAs that have been TRIM'd, modify the values ​​in the corresponding entries to special values ​​to indicate that there is no valid data; Reclaim the corresponding physical address and reply to the host to complete the TRIM command.

3. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method of claim 1.

4. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method of claim 1.

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