A mobile solid state hard disk system and a method for improving the performance and data retention of a mobile solid state hard disk

Abstract

The present invention discloses a mobile solid-state hard disk system and a method for improving the performance and data retention of a mobile solid-state hard disk, and relates to the technical field of data storage. The mobile solid-state hard disk system includes: a resistive random access memory, a redundant check algorithm module and a check comparison module; when the mobile solid-state hard disk is working normally, the resistive random access memory is used to cache data; when the mobile solid-state hard disk is powered off, the resistive random access memory is used to store the check value of the data of the low-retention page; when the mobile solid-state hard disk is powered on, the check comparison module is used to compare the check value of the data of the page in the flash memory with the check value in the resistive random access memory, and if they are different, the redundant check algorithm module is used to recover the data of the page. The present invention can effectively enhance the performance and data retention of the mobile solid-state hard disk, and improve the stability and reliability of the data.

Description

Technical Field

[0001] The present invention relates to the technical field of data storage, and in particular to a mobile solid-state hard disk system and a method for improving the performance and data retention of the mobile solid-state hard disk. Background Art

[0002] In recent years, as the price of flash memory particles continues to fall, mobile solid-state drives have become the most mainstream consumer data storage device, and have been widely used due to their high performance and light weight. However, due to the inherent physical properties of flash memory particles, during the long-term storage of data after power failure, the electrons of the storage unit will leak, resulting in data loss. At present, TLC (Triple-Level Cell) memory has the advantages of large capacity and low cost, and has become the most important medium type for current consumer mobile storage. Compared with SLC (single level cell) and MLC (Multi-Level Cell) particles used in enterprise storage, the data retention of TLC storage units has declined very seriously, which ultimately affects the stability and reliability of user data. In many typical scenarios, the data retention of consumer mobile solid-state drives is only 3 months. In actual use, a large amount of commercial shooting materials and scientific experimental data are stored in large quantities using mobile solid-state drives due to their large data volume and high transmission performance requirements. However, these data are extremely valuable and need to be stored for a long time, but due to the physical properties of flash memory particles, they are easily lost due to long power failures. What's more serious is that when data is lost due to electronic leakage in flash memory particles, even the most advanced data recovery tools cannot rescue it. Therefore, enhancing the data retention of mobile solid-state drives has become an urgent issue that needs to be addressed.

[0003] Through the analysis of a large amount of experimental data from particle manufacturers, it is known that the pages where electrons are most likely to leak are the top and bottom physical units in 3D flash memory, as well as the units with high wear in TLC pages. By identifying these physical pages that are prone to leakage and then performing redundant encoding, the data reliability in mobile solid-state drives can be greatly improved. However, redundant encoding also needs to be stored for a long time to verify and recover lost flash page data. If redundant encoding is stored on flash memory, it will not only occupy flash memory space and affect user use, but also cause the encoding data itself to be lost when the flash memory unit is almost worn out.

[0004] The current challenge is that the capacity of a general mobile solid-state drive is 1-8TB, while the capacity of resistive memory is small due to the limited process and cost, for example, 1GB. Using the industry's most advanced redundant coding algorithms, such as large-scale EC and LDPC algorithms, the redundant space also needs to account for one percent of the data space. An 8TB hard drive requires 80GB of space to store redundant coding, and the redundant coding storage overhead is too large to meet the low-cost requirements of mobile solid-state drives. Summary of the invention

[0005] The purpose of the present invention is to provide a mobile solid state hard disk system and a method for improving the performance and data retention of the mobile solid state hard disk, so as to solve the problem of long-term data preservation after the mobile solid state hard disk loses power.

[0006] To achieve the above-mentioned purpose, the present invention provides a mobile solid-state hard disk system, comprising: a resistive random access memory, a redundant check algorithm module and a check comparison module; when the mobile solid-state hard disk is working normally, the resistive random access memory is used to cache data; when the mobile solid-state hard disk is powered off, the resistive random access memory is used to store the check value of the data of the low retention force page; when the mobile solid-state hard disk is powered on, the check comparison module is used to compare the check value of the data of the page in the flash memory with the check value in the resistive random access memory, and if they are different, the data of the page is recovered through the redundant check algorithm module.

[0007] To achieve the above object, the present invention also provides a method for improving the performance and data retention of a mobile solid-state hard disk, comprising:

[0008] When the mobile solid-state drive is working normally, data is cached through the resistive memory;

[0009] When the mobile solid state drive is powered off, a check value of the data of the low retention force page is calculated and stored in the resistive random access memory;

[0010] When the mobile solid-state hard disk is powered on again, the data of the corresponding page in the flash memory is read according to the combined address mapping table in the resistive memory, and the check value is calculated;

[0011] Compare the check value of the page data with the check value in the resistive random access memory;

[0012] If they are the same, it is determined that no data is lost;

[0013] If they are different, the data of the page in the flash memory is restored using a redundancy check algorithm.

[0014] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0015] When the present invention is working normally, the resistive random access memory is used to cache data, improve the access performance of the mobile solid-state hard disk, and after power is off, it can store the verification data of the flash memory page to improve the data reliability of the mobile solid-state hard disk. The resistive random access memory is a non-volatile memory based on the reversible conversion between the high resistance state and the low resistance state of the resistance of non-conductive materials under the action of an external electric field. It has the advantages of fast reading and writing speed, non-volatility, stable storage unit, and long-term data storage, and completely replaces the DRAM cache in the mobile solid-state hard disk. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 A schematic diagram of the structure of a mobile solid-state hard disk system provided by the present invention;

[0018] Figure 2 A flow chart of a method for improving the performance and data retention of a mobile solid-state hard disk provided by the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The purpose of the present invention is to provide a mobile solid-state hard disk system and a method for improving the performance and data retention of the mobile solid-state hard disk, thereby enhancing the performance and data retention of the mobile solid-state hard disk and improving the stability and reliability of data.

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] This embodiment provides a mobile solid state hard disk system, such as Figure 1 As shown, based on the general mobile solid-state hard disk circuit, the DRAM cache memory is removed, and the resistive random access memory 1 (ReRAM), battery 7, signal light 8 and other components are newly added, and the redundant verification algorithm module 2 and the verification comparison module 3 are newly added to the mobile solid-state hard disk. Compared with the traditional hardware circuit, the resistive random access memory 1 has the characteristic of non-volatility, so the resistive random access memory 1 can be used for data cache during operation, and can also be used to store the verification data of the flash memory particles after power off, taking into account both performance and data reliability.

[0023] In this embodiment, the mobile solid-state hard disk system includes: a resistive random access memory 1, a redundancy check algorithm module 2 and a check and comparison module 3; the redundancy check algorithm module 2 and the check and comparison module 3 are arranged in a mobile solid-state hard disk 4.

[0024] When the mobile solid-state hard disk 4 is working normally, the resistive random access memory 1 is used to cache data. When the mobile solid-state hard disk 4 is connected to a notebook, PC, or embedded terminal device through an interface (USB3 / 4, Thunderbolt 3 / 4, Bluetooth, WIFI) 6, the resistive random access memory 1 is only used for data caching, and the host computer charges the battery 7. When the mobile solid-state hard disk 4 receives a read command, it first searches for data in the resistive random access memory 1, and returns the requested data if it hits; if it misses, it reads data from the flash memory 5, and writes the high-frequency read data into the resistive random access memory 1 according to the frequency of the data read operation. When the mobile solid-state hard disk 4 receives a write command, the data is first written into the resistive random access memory 1, and then the write operation is returned to the upper layer to complete, and finally the dirty data in the resistive random access memory 1 is persisted to the flash memory 5 by the background task.

[0025] When the mobile solid state drive 4 is powered off, the resistive random access memory 1 is used to store the check value of the data of the low retention force page;

[0026] When the mobile solid state drive 4 is powered on, the verification comparison module 3 is used to compare the verification value of the data on the page in the flash memory 5 with the verification value in the resistive random access memory 3. If they do not match, the redundant verification algorithm module 2 is used to recover the data on the page.

[0027] With respect to the above mobile solid state hard disk system, this embodiment also provides a method for improving the performance and data retention of the mobile solid state hard disk, such as Figure 2 As shown, the method includes:

[0028] S1: When the mobile solid state drive 4 operates normally, data is cached through the resistive random access memory 1.

[0029] S2: When the mobile solid state drive 4 is powered off, the check value of the data of the low retention force page is calculated and stored in the resistive random access memory 1.

[0030] When the mobile solid-state drive 4 is powered off, when the main control receives the power-off signal, the first step is to first clean up the read data in the resistive random access memory 1 cache, and write the dirty data back to the flash memory particles. The second step is to calculate a weight for each page based on the 3D structural layer position, wear degree, and structural state (SLC or TLC) of the data page, sort by weight, and select low-retention pages for redundancy verification, such as large-scale erasure code or LDPC coding algorithm, calculate the check value of the page data, and finally write the check value back to the resistive random access memory 1, and store the corresponding combination address table in the resistive random access memory 1. The process is powered by the battery 7, and the user can be reminded by the signal light 8.

[0031] The weight is calculated by the following formula:

[0032] x represents the weight of the layer. Since the data retention in the middle layer is high, the closer to the top layer or the bottom layer, the lower the data retention. Therefore, the formula is as follows:

[0033] x=|Current level - total level / 2|

[0034] y represents the wear weight. The more times a page is erased, the lower the data retention is. Therefore, the formula is as follows:

[0035] y = cumulative erase and write times of the current page / durability of the storage unit

[0036] z represents the storage unit state weight. If the page is in SLC mode, z is equal to 1; if the page is in TLC state, z is equal to 100;

[0037] Therefore, the weight calculation formula is as follows:

[0038] W=x*λ1+y*λ2+z*λ3;λ1>0,λ2>0,λ3>0

[0039] Among them, λ1, λ2, and λ3 represent weight coefficients.

[0040] According to the reordering results, the page with the largest weight is selected, and these pages are grouped and re-encoded according to the group, and the redundant check data is calculated. Finally, these check results are stored in the resistive random access memory to improve the data reliability of the low retention pages.

[0041] The existing algorithm solves the reliability problem of storage units by encoding all pages in the flash memory 5, which requires more storage overhead and needs to be recalculated every time data is written. The algorithm of the present invention selects cells with lower retention power for redundant encoding through weight calculation of three dimensions, and the storage unit overhead is very small, and only one calculation needs to be completed when removing.

[0042] S3: When the mobile solid state hard disk 4 is powered on again, the data of the corresponding page in the flash memory 5 is read according to the combined address mapping table in the resistive random access memory 1, and a check value is calculated.

[0043] S4: Compare the check value of the page data with the check value in the resistive random access memory.

[0044] S5: If they are the same, it is determined that no data is lost and the verification process ends.

[0045] S6: If they are different, recover the data of the page in the flash memory by using a redundancy check algorithm.

[0046] If the result is inconsistent, the data of the abnormal page in the flash memory 5 is restored by the redundancy check technology using the check value stored in the resistive random access memory 1. After the check and recovery are completed, the check content in the resistive random access memory 1 is cleared and the space is reused as a read-write cache.

[0047] The present invention uses a resistive random access memory to cache data when the mobile solid-state hard disk is working normally, which can improve the access performance of the mobile solid-state hard disk. After power is off, the verification data of the flash memory page can be stored to improve the data reliability of the mobile solid-state hard disk. In addition, the present invention selects pages with low data retention based on a three-dimensional weight screening algorithm, and stores the redundant verification codes of these units in the resistive random access memory, which consumes less storage space. In addition, the redundant coding occurs after the mobile solid-state hard disk is powered off, the number of coding calculations is small, and it will not affect the normal IO performance of the user.

[0048] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0049] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A mobile solid state hard disk system, characterized in that: include: Resistive random access memory, redundant check algorithm module and check comparison module; the redundant check algorithm module and check comparison module are arranged in a mobile solid state hard disk; When the mobile solid-state hard disk is operating normally, the resistive random access memory is used to cache data; When the mobile solid-state hard disk is powered off, the resistive random access memory is used to store the check value of the data of the low retention force page; When the mobile solid-state hard disk is powered on, the check comparison module is used to compare the check value of the data on the page in the flash memory with the check value in the resistive random access memory. If they do not match, the data on the page is recovered by the redundant check algorithm module. When the mobile solid-state hard disk is powered off, the specific steps of the resistive random access memory for storing the check value of the data of the low retention page are as follows: first, clear the read data in the resistive random access memory cache, and write the dirty data back to the flash memory particles; Step 2: Calculate a weight for each page based on the 3D structural layer position, wear level, and structural state of the flash memory of the data page, sort by weight, and select pages with low retention for redundancy check; The weight is calculated by the following formula: W=x*λ1+y*λ2+z*λ3; λ1>0, λ2>0, λ3>0; x=|current number of layers - total number of layers / 2|; y = cumulative erase and write times of the current page / endurance of the flash memory; Wherein, x represents the weight of the number of layers of the page; y represents the weight of the wear degree of the page; z represents the state weight of the flash memory, if the page is in SLC mode, z is equal to 1, if the page is in TLC state, z is equal to 100; λ1, λ2, λ3 represent weight coefficients; According to the re-sorting result, the page with the largest weight is selected, and after the pages are grouped, they are re-encoded according to the group, and the redundant check data is calculated, and finally the check results are stored in the resistive random access memory.

2. The mobile solid state hard disk system according to claim 1, characterized in that: When the mobile solid-state hard drive receives a read command, it first searches for data in the resistive random access memory. If a hit is found, the requested data is returned. If a hit is not found, the data is read from the flash memory again, and the high-frequency read data is written into the resistive random access memory according to the frequency of the data read operation.

3. The mobile solid state hard disk system according to claim 1, characterized in that: When the mobile solid-state drive receives a write command, the data is first written into the resistive random access memory, and then the write operation is completed and returned to the upper layer. Finally, the background task persists the dirty data in the resistive random access memory to the flash memory.

4. A method for improving the performance and data retention of a mobile solid-state hard disk, characterized in that: The method is applied to the mobile solid-state hard disk system according to any one of claims 1 to 3, and the method comprises: When the mobile solid-state drive is working normally, data is cached through the resistive memory; When the mobile solid state drive is powered off, a check value of the data of the low retention force page is calculated and stored in the resistive random access memory; When the mobile solid-state hard disk is powered on again, the data of the corresponding page in the flash memory is read according to the combined address mapping table in the resistive memory, and the check value is calculated; Compare the check value of the page data with the check value in the resistive random access memory; If they are the same, it is determined that no data is lost; If they are different, the data of the page in the flash memory is restored using a redundancy check algorithm.

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