WO2016107442A1 - Method for writing data to solid state drive and solid state drive - Google Patents

Abstract

A method for writing data to a solid state drive and the solid state drive. The SSD (40) comprises a controller (42) and a storage. Storage media of the storage comprise an NAND Flash (44) and an NVM (43). The NVM (43) comprises a writing area. The method comprises: receiving a writing request, the writing request comprising pre-written data (S601); determining that the pre-written data is not stored in the writing area (S602); and writing the pre-written data to the writing area (S603). By writing the pre-written data to the writing area of the NVM, the access frequency of the NAND Flash can be reduced, that is, the access frequency of the NAND Flash in the SSD is reduced, and thereby reducing wearing to the NAND Flash; moreover, because the NVM is nonvolatile, data stored in the NVM will not be lost when power is off, and the SSD does not need a capacitor to supply back-up power when power supply is interrupted. Based on the foregoing reasons, the service life of the SSD can be extended.

Description

Method for writing data to solid state hard disk and solid state hard disk Technical field

Embodiments of the present invention relate to storage technologies, and in particular, to a method for writing data to a solid state hard disk and a solid state hard disk.

Background technique

Solid State Drives (SSDs), referred to as fixed disks, are widely used in servers, desktops, notebooks, mobile devices, game consoles, etc.

As shown in FIG. 1 , the SSD 10 mostly uses the semiconductor NAND Flash 14 as a storage medium of the memory; and provides backup power through the capacitor 15 to prevent data in the memory 13 from being lost when power is lost; receiving the read by the host 11 through the controller 12 Write operation request and read and write to memory 13 or NAND Flash 14.

In the prior art, when the read/write operation request is for the NAND Flash 14, the memory 13 is used as an intermediary, and the data corresponding to the read operation request is read from the NAND Flash 14 to the memory 13, and then returned to the host 11; or, The data corresponding to the write operation request is first written into the memory 13 and then transferred to the NAND Flash 14. Thus, if the data corresponding to the write operation request buffered in the memory 13 has not been transferred to the NAND Flash 14, the power supply is interrupted, and the capacitor 15 is required to provide the backup power, and the data in the memory 13 is written to the NAND Flash 14.

However, based on historical data statistics, NAND Flash and capacitors are the main sources of failure for SSDs. Therefore, in SSDs, the presence of capacitors and excessive reading and writing of NAND Flash may result in a shorter lifetime of the SSD.

Summary of the invention

Embodiments of the present invention provide a method for writing data into a solid state hard disk and a solid state hard disk to increase the service life of the SSD and improve the reliability of the SSD.

In a first aspect, an embodiment of the present invention provides a method for writing data into a solid state hard disk SSD. The method includes a controller and a memory, the storage medium of the memory comprising a NAND flash and a non-volatile memory NVM, the NVM including a write area, the method comprising:

Receiving a write operation request, the write operation request including pre-written data;

Determining that the pre-written data is not stored in the write area;

The pre-written data is written to the write area.

According to the first aspect, in a first possible implementation manner of the first aspect, the method further includes:

Determining whether the pre-written data has been stored in the NAND Flash;

If the pre-written data is already stored in the NAND Flash, the page in the NAND Flash storing the pre-written data is invalidated.

According to the first aspect, or the first possible implementation manner of the first aspect, in the second possible implementation manner of the first aspect, after the writing the pre-write data into the write area, The method also includes:

A mapping relationship is saved, the mapping relationship including a correspondence between a logical address of the pre-written data and a location where the pre-written data is written into the write area.

According to the first aspect, the first to the second possible implementation manner of the first aspect, in a third possible implementation manner of the first aspect, the method further includes:

Determining whether the accessed frequency of the pre-written data reaches a preset threshold;

When the accessed frequency of the pre-written data reaches the preset threshold, the pre-written data is migrated to the read region.

According to the first aspect, the first to the third possible implementation manner of the first aspect, in a fourth possible implementation manner of the first aspect, the method further includes:

Determining whether the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold;

And when the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold, migrating the data in the page whose accessed frequency is greater than or equal to the preset threshold to the read region of the NVM.

In a second aspect, an embodiment of the present invention provides a method for writing data into a solid state hard disk SSD. The method includes a controller and a memory, the storage medium of the memory including a NAND flash and a non-volatile memory NVM, the NVM including a write area and a read area, the method comprising:

Receiving a write operation request, the write operation request including pre-written data;

Determining that the pre-written data has been stored in the read area;

The pre-written data in the read region is migrated to the write region.

According to the second aspect, in a first possible implementation manner of the second aspect, after the pre-writing data in the read area is migrated to the write area, the method further includes:

Updating the first mapping relationship to a second mapping relationship, where the first mapping relationship includes a correspondence between a logical address of the pre-written data and a location of the pre-written data in the read region, where The second mapping relationship includes a correspondence between a logical address of the pre-written data and a location of the pre-written data in the write area.

According to the second aspect or the first possible implementation manner of the second aspect, in a second possible implementation manner of the second aspect, the method further includes:

Determining whether the accessed frequency of the pre-written data reaches a preset threshold;

When the accessed frequency of the pre-written data reaches the preset threshold, the pre-written data is migrated to the read region.

According to the second aspect, the first to the second possible implementation manner of the second aspect, in a third possible implementation manner of the second aspect, the method further includes:

Determining whether the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold;

And when the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold, migrating the data in the page whose accessed frequency is greater than or equal to the preset threshold to the read region of the NVM.

According to the second aspect, the first to the third possible implementation manner of the second aspect, in a fourth possible implementation manner of the second aspect, the NVM further includes a free area, where After the pre-written data in the read area is migrated to the write area, the method further includes:

In the free area, N pages are adjusted from the pages reserved for the write area to the read area, and the N is the number of pages corresponding to the pre-written data.

In a third aspect, an embodiment of the present invention provides a solid state hard disk SSD, where the SSD includes a controller and a memory, and the storage medium of the memory includes a NAND flash and a nonvolatile memory NVM, where the NVM includes a write area, where

The controller is configured to receive a write operation request, the write operation request includes pre-writing data, determine that the pre-write data is not stored in the write area, and write the pre-write data into the Describe area

The write area is for storing the pre-written data.

According to the third aspect, in a first possible implementation manner of the third aspect, the controller is further configured to:

Determining whether the pre-written data has been stored in the NAND Flash;

If the pre-written data is already stored in the NAND Flash, the page in the NAND Flash storing the pre-written data is invalidated.

According to the third aspect or the first possible implementation manner of the third aspect, in a second possible implementation manner of the third aspect, the controller is further configured to:

A mapping relationship is saved, the mapping relationship including a correspondence between a logical address of the pre-written data and a position at which the pre-written data is written into the write area.

According to the third aspect, the first to the second possible implementation manner of the third aspect, in a third possible implementation manner of the third aspect, the controller is further configured to:

Determining whether the accessed frequency of the pre-written data reaches a preset threshold;

When the accessed frequency of the pre-written data reaches the preset threshold, the pre-written data is migrated to the read region.

According to the third aspect, the first to the third possible implementation manner of the third aspect, in a fourth possible implementation manner of the third aspect, the controller is further configured to:

Determining whether the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold;

When the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold, migrating the data in the page whose accessed frequency is greater than or equal to the preset threshold to the location The read area of the NVM.

In a fourth aspect, an embodiment of the present invention provides a solid state hard disk SSD, where the SSD includes a controller and a memory, and the storage medium of the memory includes a NAND flash and a nonvolatile memory NVM, and the NVM includes a write area and a read area. ,among them,

The controller is configured to receive a write operation request, the write operation request includes pre-writing data, determine that the pre-write data has been stored in the read area, and: perform the pre-in the read area The write data is migrated to the write area.

According to the fourth aspect, in a first possible implementation manner of the fourth aspect, the controller is further configured to:

Updating the first mapping relationship to a second mapping relationship, where the first mapping relationship includes a correspondence between a logical address of the pre-written data and a location of the pre-written data in the read region, where The second mapping relationship includes a correspondence between a logical address of the pre-written data and a location of the pre-written data in the write area.

According to the fourth aspect or the first possible implementation manner of the fourth aspect, in a second possible implementation manner of the fourth aspect, the controller is further configured to:

Determining whether the accessed frequency of the pre-written data reaches a preset threshold;

When the accessed frequency of the pre-written data reaches the preset threshold, the pre-written data is migrated to the read region.

According to the fourth aspect, the first to the second possible implementation manner of the fourth aspect, in a third possible implementation manner of the fourth aspect, the controller is further configured to:

Determining whether the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold;

And when the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold, migrating the data in the page whose accessed frequency is greater than or equal to the preset threshold to the read region of the NVM.

According to the fourth aspect, the first to the third possible implementation manner of the fourth aspect, in a fourth possible implementation manner of the fourth aspect, the NVM further includes a free area, the control Also used to:

In the free area, N pages are adjusted from pages reserved for the write area In the reading area, the N is the number of pages corresponding to the pre-written data.

Embodiments of the present invention provide a method for writing data into a solid state hard disk and a solid state hard disk, and writing prewritten data to a write area of the NVM, thereby reducing access to the NAND Flash, that is, reducing the accessed frequency of the NAND Flash in the SSD. Reduce the wear and tear on NAND Flash; and, due to the non-volatile nature of NVM, the data stored in NVM is not lost. Therefore, in the event of power interruption, SSD does not need capacitors to provide backup power. For the above reasons, the service life of the SSD of the embodiment of the present invention is increased.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief description of the drawings used in the embodiments or the prior art description will be briefly described below. Obviously, the drawings in the following description It is a certain embodiment of the present invention, and other drawings can be obtained from those skilled in the art without any inventive labor.

FIG. 1 is a schematic diagram of an application scenario of a prior art SSD;

2 is a schematic diagram of data stored in a storage unit of an SLC;

3 is a schematic diagram of data stored in a storage unit of an MLC;

4 is a schematic structural view of an SSD according to the present invention;

5 is a diagram showing an example of the structure of an NVM in an SSD according to the present invention;

6 is a flowchart of Embodiment 1 of a method for writing data into an SSD according to the present invention;

7 is a flowchart of Embodiment 2 of a method for writing data into an SSD according to the present invention;

FIG. 8 is a diagram showing an example of a mapping relationship in an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. It is a partial embodiment of the invention, and not all of the embodiments. Based on the embodiments of the present invention, those of ordinary skill in the art are not All other embodiments obtained under the premise of creative labor are within the scope of the invention.

In the prior art, NAND Flash is a physical medium in which an SSD actually stores data. Among them, NAND Flash includes single-level cell storage (English: Single Level Cell, SLC for short), multi-level cell storage (English: Multi Level Cell, MLC for short), and three-layer cell storage (English: Triple Level Cell) , referred to as: TLC) several. In the enterprise storage area, SLC and MLC are mainly used. TLC has a low number of erases and is currently used primarily in consumer electronics.

The SLC technology is characterized in that the oxide film in the floating gate and the source is thinner, and the stored charge is removed by applying a voltage to the charge of the floating gate when writing data, and then passing through the source. In this way, one information unit can be stored, which provides fast program programming and reading. However, this technology is limited by silicon efficiency (English: Silicon efficiency), and it is necessary to use advanced process enhancement technology to upgrade SLC processing technology.

The SLC stores 1 bit (English: bit) of data in each storage unit, and whether the stored data is "0" or "1" is determined based on a voltage threshold. For NAND Flash write, ie programming, is to charge it, so that the voltage of NAND Flash exceeds the voltage decision point A shown in Figure 2, the memory cell means "0", that is, it has been written; if there is no charge or voltage When the threshold is lower than the voltage decision point A, it means "1", that is, erase, and the horizontal axis in Fig. 2 represents voltage.

In September 1997, Intel first developed the MLC. Its function is to store two units of information into a floating gate (English: Floating Gate), and then use the charge of different potentials to control the voltage stored in the memory. Read and write. MLC uses a large number of voltage levels, each unit stores two bits of data, and the data density is relatively large. The SLC stores two values of 0 and 1, while the MLC can store more than four values at a time. Therefore, MLC has a relatively high storage density.

As shown in FIG. 3, the MLC stores 2 bits of data in each storage unit, and the stored data is "00", or "01", or "10", or "11" is also a determination based on a voltage threshold. When the voltage is less than the voltage decision point B, it represents "11"; when the voltage is at the voltage decision point Between B and the voltage determination point C, it represents "10"; when the voltage is between the voltage determination point C and the voltage determination point D, it means "01"; and when the voltage reaches the voltage determination point D or more, it means "00".

A memory cell of the TLC can store 3 bits, so it requires 8 levels of potential for encoding and decoding. In essence, TLC belongs to MLC.

The current research on new storage media is on the rise, and various new technologies or new types of storage media are emerging. The new storage medium includes, for example, phase change memory (English: Phase Change Random Access Memory, PCROM/PCM), magnetoresistive random access memory (MRAM), and resistive random access memory. The present invention is not limited in terms of memory (English: Resistive Random Access Memory, RRAM/ReRAM for short) and spin transfer torque random access memory (STT-RAM).

The above-mentioned several new types of storage media belong to non-volatile storage media (English: non-volatile memory, referred to as: NVM). In the foreseeable future, NAND Flash will exist for a long time as the main storage medium based on the protection of existing investment and cost considerations. At the same time, new non-volatile storage media will gradually play an important role until the NAND Flash is gradually replaced. In this evolution, there may be cases where multiple media coexist on the same SSD.

For the above reasons, an embodiment of the present invention provides an SSD.

As shown in FIG. 4, the SSD 40 includes a controller 42 and a memory, and the storage medium of the memory includes a NAND Flash 44 and an NVM 43.

Among them, NVM is different from ordinary memory in that the NVM medium itself has the characteristics of power loss without losing data. Based on this feature, NVM has the following features: cache write, make a complete page in NVM, and then judge whether to transfer to NAND Flash according to the accessed frequency of the page and the size of NVM; accelerate read, will be accessed High frequency data is migrated to NVM.

Figure 5 shows the area division of the NVM. As shown in FIG. 5, the NVM 50 may include four logical areas: a metadata area 51, a read area 52, a write area 53, and a free area 54, Implement partition management for NVM. The role of each region is as follows:

The metadata area 51 is used to store metadata of the SSD. For example, the metadata may be a mapping relationship, a first input first output (referred to as a FIFO) doubly linked list, and the like.

The read area 52 is used for read acceleration, and the page whose access frequency (ie, the number of reads) in the SSD is higher than or equal to the preset threshold is migrated to the read area 52.

The write area 53, all write operations to the SSD, is written to the write area 53 first. The elimination of the area after it is full is eliminated according to the strategy of least recently accessed frequency.

The free area 54, which is shared by the read area 52 and the write area 53, provides a free page for a read operation or a write operation, and the read operation and the write operation perform free area sharing according to the ratio of the read area 52 and the write area 53.

It is added that the ratio of the write area to the read area in the NVM is adjustable. Normally, the write area is much larger than the read area. In particular, there can be only write areas and no read areas in the NVM. In addition, different application scenarios require different performance requirements and erasing times for SSDs. Therefore, based on the service life of SSD, the performance of SSD, and the cost considerations, SSDs that meet the required number of erasing times can be equipped according to the actual business needs of users, and the ratio of NVM and NAND can be matched to provide users with cost-effective products. To avoid the extra expenses caused by over-provisioning and improve resource utilization.

Specifically, the controller 42 is configured to execute the technical solution protected by the following method embodiments, for example, the technical solution shown in FIG. 6, to implement writing of data to the write area of the NVM 43, the write area for storing pre-write Into the data. Among them, NVM has the ability to write data in units of bits (bits) and can be rewritten in bits.

As shown in FIG. 6, an embodiment of the present invention provides a method for writing data to an SSD, which may be performed by a controller in an SSD. The method includes:

S601. Receive a write operation request, where the write operation request includes pre-written data.

S602. Determine that the pre-written data is not stored in the write area.

S603. Write pre-write data to the write area.

Specifically, all write operations to the SSD 40 are written to the write area first.

For the above pre-written data to be written to the SSD 40, the pre-written data may have It is stored in the write area, and therefore, in S602, it is first determined that the pre-write data is not stored in the write area.

In the embodiment of the present invention, writing pre-write data to the write area of the NVM can reduce access to the NAND Flash, that is, reduce the accessed frequency of the NAND Flash in the SSD, thereby reducing wear on the NAND Flash; and, due to the non-volatile of the NVM The data stored in the NVM is not lost. Therefore, the SSD does not need a capacitor to provide backup power when the power supply is interrupted. For the above reasons, the service life of the SSD of the embodiment of the present invention is increased.

In the above embodiment, the method of writing data to the SSD may further include: determining whether the pre-written data is stored in the NAND Flash; if the pre-written data is stored in the NAND Flash, storing the pre-written data in the NAND Flash. The page is set to invalid. This embodiment can avoid storing two identical data in the SSD, thereby causing waste of storage space.

Further, after S603, the method may further include: saving a mapping relationship, where the mapping relationship includes a correspondence between a logical address of the pre-written data and a position where the pre-written data is written in the write area. Referring to FIG. 4 at the same time, according to the mapping relationship, the controller 42 can conveniently read and write the NVM 43 and the NAND Flash 44.

Since the read area of the NVM 43 is used to store data whose accessed frequency (ie, the number of reads) is higher than or equal to a preset threshold, the NAND Flash 44 is used to store data whose accessed frequency (ie, the number of readings) is lower than a preset threshold, and thus The method may further include: determining whether the accessed frequency of the pre-written data reaches a preset threshold; when the accessed frequency of the pre-written data reaches a preset threshold, migrating the pre-written data to the read area to implement pre-writing The incoming data migrates from the write area to the read area, speeding up the reading of the pre-written data.

Similarly, the method may further include: determining whether the accessed frequency of the page in the NAND Flash is greater than or equal to a preset threshold; when the accessed frequency of the page in the NAND Flash is greater than or equal to a preset threshold, the migrated access frequency is greater than or equal to Presetting the threshold data into the read area of the NVM to implement data migration from NAND Flash to the read area, speeding up the reading of the data, utilizing the temporal locality and spatial locality of the data, and frequently modifying the data. And other hotspot data is stored in NVM, reducing wear and tear on NAND Flash.

In addition, the controller 42 can also be used to perform the steps as shown in FIG. As shown in Figure 7 The embodiment of the invention provides a method for writing data into an SSD, the method comprising:

S701. Receive a write operation request, where the write operation request includes pre-write data.

S702. Determine that the pre-written data is stored in the read area.

S703. The pre-written data in the read area is migrated to the write area.

Specifically, the node corresponding to the pre-written data in the second doubly linked list may be updated to the tail of the first doubly linked list. Each node in the first doubly linked list is used to store a logical address of each page in the write area; each node in the second doubly linked list is used to store a logical address of each page in the read area. To achieve mutual migration of data stored in the read area and the write area in the NVM.

If the pre-written data is already stored in the read area of the NVM, it is migrated to the write area. In the specific implementation, only the nodes in the read area are migrated to the write area.

The embodiment of the present invention migrates the pre-written data stored in the read area to the write area. The migration involves only two different areas in the NVM, and is independent of the NAND Flash. Therefore, the NAND Flash access can be reduced, that is, the NAND Flash in the SSD is reduced. The frequency of access is reduced, thereby reducing the wear and tear on NAND Flash; and, due to the non-volatile nature of NVM, the data stored in the NVM is not lost, so the SSD does not need a capacitor to provide backup power when the power supply is interrupted. For the above reasons, the service life of the SSD of the embodiment of the present invention is increased.

In the foregoing embodiment, after S703, the method may further include: updating the first mapping relationship to the second mapping relationship. The first mapping relationship includes a correspondence between a logical address of the pre-written data and a location of the pre-written data in the read area; the second mapping relationship includes a logical address of the pre-written data and a pre-written data in the write area. The correspondence between the locations. Referring to FIG. 4 at the same time, according to the mapping relationship, the controller 42 can conveniently read and write the NVM 43 and the NAND Flash 44.

Since the read area of the NVM 43 is used to store data whose accessed frequency (ie, the number of reads) is higher than or equal to a preset threshold, the NAND Flash 44 is used to store data whose accessed frequency (ie, the number of readings) is lower than a preset threshold, and thus The method may further include: determining whether the accessed frequency of the pre-written data reaches a preset threshold; when the accessed frequency of the pre-written data reaches a preset threshold, migrating the pre-written data to the read area to implement pre-writing The incoming data migrates from the write area to the read area, speeding up the reading of the pre-written data.

Similarly, the method may further include: determining the accessed frequency of the page in the NAND Flash Whether it is greater than or equal to the preset threshold; when the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold, the data in the page whose accessed frequency is greater than or equal to the preset threshold is migrated to the read area of the NVM to implement data from NAND Flash migrates to the read area, speeds up the reading of the data, and utilizes the temporal locality and spatial locality of the data to store frequently modified data and other hotspot data in the NVM, reducing wear and tear on the NAND Flash.

Further, the NVM 43 may further include a free area. After S703, the method may further include: adjusting, in the free area, N pages to the read area from the page reserved for the write area, wherein N is a pre-written data corresponding to The number of pages.

For the case where the above pre-written data has been stored in the SSD, the controller 42 also needs to acquire the storage location to determine the subsequent operation. Specifically, it is explained from the following application scenarios.

In the first application scenario, pre-written data is stored in the NAND Flash in the SSD. The application scenario includes at least two implementations.

In the first implementation, pre-written data occupies a complete page in NAND Flash. At this time, the mapping relationship is updated, that is, the logical address of the pre-written data is pointed to the position where the pre-written data is written to the write area. The mapping relationship includes the correspondence between logical addresses and physical addresses of all pages in the SSD.

In the second implementation, the pre-written data occupies a non-complete page in the NAND Flash. At this time, data other than the portion of the NAND Flash corresponding to the range of the logical address of the pre-written data is transferred to the write area of the NVM in the page corresponding to the pre-written data; in the write area, the combination is written. The pre-written data and the data migrated to the write area constitute a new page; then, the direction of the logical address of the pre-written data in the mapping relationship is updated to point to the address of the above new page.

The difference between the foregoing two implementation manners is that the first implementation manner is used to indicate that the size of the pre-written data is exactly an integer multiple of the page in the NAND Flash. In this case, only the logical address and the physical address in the mapping relationship need to be updated. Corresponding relationship may be, in the mapping relationship, increasing the correspondence between the logical address of the pre-written data and its physical address in the NVM; the second implementation manner is used to indicate that the size of the pre-written data is not a page in the NAND Flash The processing of integer multiples.

For example, the size of the pre-written data is 4 KB, and the pre-written data is stored in the first page of the NAND Flash, and the size of the page in the NAND Flash is 8 KB, and the first page corresponds to a logical address and a physical address in the mapping relationship. . When writing the pre-written data, data other than the same portion of the first page as the logical address of the pre-written data is migrated to the write area; in the write area, the pre-written data and the migration are combined The data to the write area constitutes a new page; then, the mapping of the logical address of the pre-written data in the mapping relationship preset relationship is updated to point to the address of the combined new page.

Optionally, the address of the new page is saved to the tail of the first doubly linked list, and each node in the first doubly linked list is used to store the logical address of each page in the write area.

Specifically, each node in the first doubly linked list is used to represent a page in the write area. The node has a predecessor pointer and a successor pointer. The predecessor pointer points to the predecessor node of the first doubly linked list, and the subsequent pointer points to the subsequent node of the first doubly linked list; in addition, the node also includes the logical address of the page. The size of the write area determines the number of nodes contained in the first doubly linked list. The first doubly linked list is used to record the order of the pages in the write area, thereby facilitating the management of the write area. For example, when data is written, the information of the corresponding page is inserted into the tail of the first doubly linked list; when it is eliminated, the page is selected from the header of the first doubly linked list.

In the second application scenario, the pre-written data is already stored in the write area of the NVM in the SSD. The application scenario includes at least the following implementation manner: receiving a write operation request sent by the requester, the write operation request includes pre-writing data, determining that the pre-write data is stored in a write area, and storing pre-write in the write area. The location of the data is rewritten to the pre-written data.

The node corresponding to the pre-written data in the first doubly linked list is adjusted to the tail of the first doubly linked list. In this application scenario, internal migration of data stored in the write area is implemented. If the pre-written data is already stored in the write area, it is migrated to the corresponding node in the first doubly linked list to the end of the first doubly linked list.

Optionally, after S603, the method may further include: saving an address of the page corresponding to the pre-written data to a tail of the first doubly linked list.

And updating the count of the written pages in the NVM according to the number of pages corresponding to the pre-written data; if the judgment count is greater than or equal to the first threshold, migrating the first threshold number of pages from the NVM to the NAND Flash to implement the NVM There is enough space for new data to be written and / Or the migration of data stored in other areas of the SSD to achieve dynamic adjustment of the stored data in the SSD.

Specifically, before the pre-write data is written into the write area, if it is determined that the write area is full, starting from the header of the first doubly linked list, determining that the number of times the page corresponding to the node in the first doubly linked list is greater than or equal to the second threshold Transmitting the data in the page of the page corresponding to the pre-written data to the read area; saving the address of the page in the read area to the second doubly linked list, and the nodes in the second doubly linked list are used The logical address of each page in the storage read area. Similar to the write area, the read area corresponds to the second doubly linked list, and the structure of the second doubly linked list is the same as that of the first doubly linked list, and details are not described herein again.

If the data in the page corresponding to the pre-written data is migrated to the read area, if it is judged that the read area is full, or if it is determined that the write area is full, the first doubly linked list is determined from the first part of the first doubly linked list. If the number of times of reading the page corresponding to the node is less than the second threshold, the data in the page corresponding to the number of pages corresponding to the pre-written data is migrated to the NAND Flash from the header of the second doubly linked list to update the data in the read area in real time. When the storage space is insufficient, the data with low access frequency is migrated to NAND Flash in time to further ensure the performance of the SSD.

At the same time, the number of migrations corresponding to the NAND Flash is accumulated; if it is determined that the number of migrations is greater than or equal to the third threshold, the page of the third threshold is selected from the NVM to migrate to the NAND Flash, and the selected page is the first corresponding to the write region. The third threshold number of pages starting from the header of the doubly linked list, wherein the third threshold is determined by the ratio of NVM to NAND Flash in the SSD. This embodiment balances the data stored in the NAND Flash and the NVM in the SSD, and prevents the data from being completely stored in the NVM, thereby causing waste of the storage space of the NAND Flash.

In the second application scenario, the pre-written data is stored in the write area. At this time, while covering the write, consider whether the storage space in each area of the NVM and the NAND Flash is sufficient, and perform the data stored therein according to the above description. The adjustment ensures that each storage medium in the SSD has enough space to meet the above requirements.

In summary, the data stored in the SSD is essentially stored in NVM or NAND Flash. Specifically, the NVM stores data that is accessed frequently, and the NAND Flash stores data that is accessed less frequently. The frequency of the frequency of access can be judged in a variety of ways. For example, a preset threshold is set, and a storage location of the data is obtained according to a comparison between the frequency of the accessed data and the preset threshold in a fixed time. At this time, the accessed frequency of the page where the data is located is saved in the mapping relationship; or The frequency at which the data is located in the above mapping relationship reflects the frequency of access of the data, and the like, and the present invention is not limited. The reading of the stored data in the SSD of the present invention is described below in several specific embodiments.

Based on the foregoing embodiment, the method may further include: accumulating the number of readings of the page where the pre-read data is located, wherein the mapping relationship includes the number of readings of all pages in the SSD. In this embodiment, the accessed frequency of the data may be represented by the number of readings, and the number of readings is included in the preset mapping relationship. Optionally, the accessed frequency of the data may also be implemented in other forms, and details are not described herein again.

The mapping relationship may be expressed in the form of a mapping table as shown in FIG. 8. In Fig. 8, each block represents a basic mapping unit whose size is, for example, 4 KB or 8 KB. Correspondingly, a structure may also be used to represent a field corresponding to a preset mapping relationship. The field corresponding to the single mapping relationship includes a physical address of the NVM or the NAND; an indication bit for indicating that the page corresponding to the block is located in the NVM or the NAND, for example, the indicator bit can be represented by one bit; and The read count of the page corresponding to this box. It should be noted that the size of the page varies with the size of the page in the NAND. The size of the page in the prior art is usually 4 KB/8 KB, but the present invention is not limited thereto.

In one embodiment, the physical address of the pre-read data is located in the NAND Flash. After accumulating the number of readings of the page where the pre-read data is located, the method may further include: determining, for each page where the pre-read data is located, if the number of readings of the page where the pre-read data is located is greater than or equal to a second threshold, and If there is a free page in the NVM, the data in the page whose read count is greater than or equal to the second threshold is migrated to the free page in the NVM. The embodiment of the present invention migrates the data stored in the NAND Flash and whose accessed frequency is higher than the second threshold to the NVM, so as to implement dynamic adjustment of the stored data in the SSD, and avoid excessive access of the NAND Flash. Saving the data whose read count is greater than or equal to the second threshold to the NVM, compared with the NAND Flash, can improve the speed of data reading, and utilize the temporal locality and spatial locality of the data to frequently modify the data. And other hotspot data is stored in NVM, reducing wear and tear on NAND Flash.

Optionally, after the data in the NAND Flash is migrated to the NVM, the number of migrations corresponding to the NAND Flash may also be accumulated. In this way, the number of pages migrating from NAND Flash to NVM can be obtained, thereby reasonably adjusting the proportion of space occupied by NAND Flash and NVM in SSD, or migrating data of the same number of pages in NVM to NAND Flash.

Further, when the read area is included in the NVM, if it is determined that the read count of the page where the pre-read data is located is greater than or equal to the second threshold, and there is a free page in the NVM, the number of times the read count is greater than or equal to the second threshold is The migration of the data to the NVM may include: if it is determined that the number of times the page in which the pre-read data is located is greater than or equal to the second threshold, and the read area includes a free page, the number of times the read count is greater than or equal to the second threshold The data is migrated to the free page of the read area.

On the basis of the above, if it is determined that the number of migrations is greater than or equal to the third threshold, the third threshold is selected from the NVM to migrate to the NAND Flash, wherein the third threshold is determined by the ratio of the NVM to the NAND Flash in the SSD. . In the SSD, if the space occupied by the NVM is larger than the space occupied by the NAND Flash, the third threshold is small; correspondingly, if the space occupied by the NVM is smaller than the space occupied by the NAND Flash, the third threshold is larger.

In another embodiment, the NVM includes a write area. If the physical address of the pre-read data is located in the write area of the NVM, after the number of times of reading the page where the pre-read data is accumulated, the method may further include: updating the address of the page where the pre-read data is located to the first doubly linked list. a tail, wherein each node in the first doubly linked list is used to store a logical address of each page in the write area.

According to the foregoing embodiment, the metadata area may include the first doubly linked list, the second doubly linked list, the preset mapping relationship, and the like.

According to the foregoing embodiment, the embodiment of the present invention stores data with high access frequency in the NVM, thereby reducing access to the NAND Flash, that is, reducing the accessed frequency of the NAND Flash in the SSD, and reducing wear and tear on the NAND Flash; and, due to the NVM The non-volatile feature, the data stored in the NVM is not lost, so the SSD does not need a capacitor to provide backup power when the power supply is interrupted. For the above reasons, the service life of the SSD of the embodiment of the present invention is increased.

In practical applications, the embodiment of the present invention does not limit the size of reading and writing. It can be any size read or write. However, the default mapping relationship of the SSD, such as the mapping table, has a basic management granularity, such as 4 KB, or 8 KB, or even 16 KB. This management granularity is generally the same as the size of the NAND Flash page, and can be different. In addition, the basic management unit for SDD reading and writing is the page.

The size of the read and write operation request sent by the host to the SSD may be arbitrary. Take the page size as 8KB as an example. If the data to be read is relatively large, it is 32KB, then you need to read 4 pages and feed the relevant data back to the host; if the data read is relatively small, For 2KB, only the corresponding 2KB of data is returned to the host.

In the embodiment of the present invention, the SSD uses NAND Flash and NVM to store data hierarchically, that is, the data is stored in NAND Flash or NVM. Due to the non-volatile characteristics of the NVM, the SSD does not include a capacitor. The problem of data loss is lost, and the absence of capacitors in the SSD will increase the service life of the SSD and greatly improve the reliability of the SSD.

In the several embodiments provided herein, it should be understood that the disclosed apparatus and methods may be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the unit or module is only a logical function division. In actual implementation, there may be another division manner, for example, multiple units or modules may be used. Combinations can be integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or module, and may be electrical, mechanical or otherwise.

The modules described as separate components may or may not be physically separated. The components displayed as modules may or may not be physical modules, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the embodiment.

One of ordinary skill in the art will appreciate that all or part of the steps to implement the various method embodiments described above may be accomplished by hardware associated with the program instructions. The aforementioned program can be stored in a computer readable storage medium. The program, when executed, performs the steps including the foregoing method embodiments; and the foregoing storage medium includes: ROM, RAM, disk or A variety of media such as optical discs that can store program code.

Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention, and are not intended to be limiting; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that The technical solutions described in the foregoing embodiments may be modified, or some or all of the technical features may be equivalently replaced; and the modifications or substitutions do not deviate from the technical solutions of the embodiments of the present invention. range.

Claims (20)

A method of writing data to a solid state drive SSD, the SSD comprising a controller and a memory, wherein the storage medium of the memory comprises a NAND flash and a non-volatile memory NVM, the NVM comprising a write area, The methods include: Receiving a write operation request, the write operation request including pre-written data; Determining that the pre-written data is not stored in the write area; The pre-written data is written to the write area. The method of claim 1 further comprising: Determining whether the pre-written data has been stored in the NAND Flash; If the pre-written data is already stored in the NAND Flash, the page in the NAND Flash storing the pre-written data is invalidated. The method according to claim 1 or 2, wherein after the writing of the pre-written data to the write area, the method further comprises: A mapping relationship is saved, the mapping relationship including a correspondence between a logical address of the pre-written data and a location where the pre-written data is written into the write area. The method according to any one of claims 1 to 3, wherein the method further comprises: Determining whether the accessed frequency of the pre-written data reaches a preset threshold; When the accessed frequency of the pre-written data reaches the preset threshold, the pre-written data is migrated to the read region. The method according to any one of claims 1 to 4, wherein the method further comprises: Determining whether the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold; And when the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold, migrating the data in the page whose accessed frequency is greater than or equal to the preset threshold to the read region of the NVM. A method of writing data to a solid state drive SSD, the SSD including a controller And a memory, wherein the storage medium of the memory comprises a NAND flash and a non-volatile memory NVM, the NVM comprising a write area and a read area, the method comprising: Receiving a write operation request, the write operation request including pre-written data; Determining that the pre-written data has been stored in the read area; The pre-written data in the read region is migrated to the write region. The method according to claim 6, wherein after the migrating the pre-written data in the read area to the write area, the method further comprises: Updating the first mapping relationship to a second mapping relationship, where the first mapping relationship includes a correspondence between a logical address of the pre-written data and a location of the pre-written data in the read region, where The second mapping relationship includes a correspondence between a logical address of the pre-written data and a location of the pre-written data in the write area. The method according to claim 6 or 7, wherein the method further comprises: Determining whether the accessed frequency of the pre-written data reaches a preset threshold; When the accessed frequency of the pre-written data reaches the preset threshold, the pre-written data is migrated to the read region. The method of any of claims 6-8, wherein the method further comprises: Determining whether the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold; And when the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold, migrating the data in the page whose accessed frequency is greater than or equal to the preset threshold to the read region of the NVM. The method according to any one of claims 6 to 9, wherein the NVM further comprises a free area, after the pre-written data in the read area is migrated to the write area, The method also includes: In the free area, N pages are adjusted from the pages reserved for the write area to the read area, and the N is the number of pages corresponding to the pre-written data. A solid state drive SSD, the SSD comprising a controller and a memory, wherein the storage medium of the memory comprises a NAND flash and a non-volatile memory NVM, wherein the NVM comprises a write area, wherein The controller is configured to receive a write operation request, the write operation request includes pre-writing data, determine that the pre-write data is not stored in the write area, and write the pre-write data into the Describe area The write area is for storing the pre-written data. The SSD of claim 11 wherein said controller is further configured to: Determining whether the pre-written data has been stored in the NAND Flash; If the pre-written data is already stored in the NAND Flash, the page in the NAND Flash storing the pre-written data is invalidated. The SSD according to claim 11 or 12, wherein the controller is further configured to: A mapping relationship is saved, the mapping relationship including a correspondence between a logical address of the pre-written data and a position at which the pre-written data is written into the write area. The SSD according to any one of claims 11 to 13, wherein the controller is further configured to: Determining whether the accessed frequency of the pre-written data reaches a preset threshold; When the accessed frequency of the pre-written data reaches the preset threshold, the pre-written data is migrated to the read region. The SSD according to any one of claims 11 to 14, wherein the controller is further configured to: Determining whether the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold; And when the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold, migrating the data in the page whose accessed frequency is greater than or equal to the preset threshold to the read region of the NVM. A solid state hard disk SSD, the SSD including a controller and a memory The memory medium of the memory includes a NAND flash and a non-volatile memory NVM, and the NVM includes a write area and a read area, where The controller is configured to receive a write operation request, the write operation request includes pre-writing data, determine that the pre-write data has been stored in the read area, and: perform the pre-in the read area The write data is migrated to the write area. The SSD of claim 16, wherein the controller is further configured to: Updating the first mapping relationship to a second mapping relationship, where the first mapping relationship includes a correspondence between a logical address of the pre-written data and a location of the pre-written data in the read region, where The second mapping relationship includes a correspondence between a logical address of the pre-written data and a location of the pre-written data in the write area. The SSD according to claim 16 or 17, wherein the controller is further configured to: Determining whether the accessed frequency of the pre-written data reaches a preset threshold; When the accessed frequency of the pre-written data reaches the preset threshold, the pre-written data is migrated to the read region. The SSD according to any one of claims 16 to 18, wherein the controller is further configured to: Determining whether the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold; And when the accessed frequency of the page in the NAND Flash is greater than or equal to the preset threshold, migrating the data in the page whose accessed frequency is greater than or equal to the preset threshold to the read region of the NVM. The SSD according to any one of claims 16 to 19, wherein the NVM further includes a free area, and the controller is further configured to: In the free area, N pages are adjusted from the pages reserved for the write area to the read area, and the N is the number of pages corresponding to the pre-written data.

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