CN103635887B - Method and storage system for caching data - Google Patents

Abstract

The embodiment of the invention provides a data caching method and a storage system. The storage system includes a plurality of controllers, and each of the controllers comprises buffer memory. The method comprises steps that a first controller receives a reading data demand carrying address information; a second controller is determined according to the address information carried by the reading data demand; the address information is transmitted to the second controller; and the second controller obtains address information of target data to be read according to the address information, and the target data can be read to buffer memory according to the address information of the target data. Target data of to be read can be accurately predicted.

Description

Method and storage system for caching data

technical field

The present invention relates to storage technology, in particular to a method for caching data and a storage system.

Background technique

High-speed cache memory (cached for short, also known as cache) is a buffer memory between the CPU and the main memory (for example, hard disk) in the storage system. It is smaller in size but faster than the hard disk. Normally, when the CPU processes a read data request, if it finds available data in the cache (called a cache hit), it can immediately return the result of the read data request, and only sends the read data request to the hard disk for reading when there is a miss. write data. Since the cache access speed is much faster than the hard disk read and write speed, the higher the cache hit rate, the higher the performance of the storage system. Therefore, the existing method is to read data that is "soon to be accessed" into the cache in advance, and subsequent read data requests can be hit immediately. This method is called prefetching.

For a storage system containing multiple controllers, if multiple controllers are in active/standby (A/P) mode, that is, only one controller is in working state, then for a storage system, the data stored in the cache All are stored centrally in the cache of the controller, so the cache data can be prefetched by identifying the sequence flow of the read data request. However, if multiple controllers are in master/master (A/A) mode, and each controller is active, the read data request may be distributed to each controller, so each controller performs the read data request When prefetching is performed by sequence flow identification, the information based on it is not comprehensive enough, so the prefetched data is not accurate enough.

Contents of the invention

Embodiments of the present invention provide a method for caching data and a storage system, so as to accurately predict target data to be read when the storage system includes multiple controllers.

The first aspect of the embodiments of the present invention provides a method for caching data, the method is applied in a storage system, and the storage system includes a plurality of controllers, wherein each controller includes a cache; the method includes:

The first controller receives a read data request sent by the host, where the read data request carries address information; determines a second controller according to the address information carried in the read data request; and sends the address information to the second controller;

The second controller obtains address information of the target data to be read according to the address information, so as to read the target data into the cache according to the address information of the target data.

In the first implementation manner of the first aspect of the embodiments of the present invention, the address information carried in the read data request includes the start address carried in the read data request;

The determining the second controller according to the address information carried in the read data request includes:

The second controller is determined according to the start address carried in the data read request and according to a set hash algorithm.

With reference to the first implementation manner of the first aspect of the embodiments of the present invention, in the second implementation manner of the first aspect of the embodiments of the present invention, the set hash algorithm includes a consistent hash algorithm.

In the third implementation manner of the first aspect of the embodiments of the present invention, the address information carried in the read data request includes the start address carried in the read data request;

The determining the second controller according to the address information carried in the read data request includes:

Querying a preset configuration table according to the starting address to obtain the second controller corresponding to the starting address.

In the fourth implementation manner of the first aspect of the embodiments of the present invention, the reading the target data into the cache according to the address information of the target data includes:

The second controller reads the target data into the cache of the second controller according to the address information of the target data.

In the fifth implementation manner of the first aspect of the embodiments of the present invention, the reading the target data into the cache according to the address information of the target data includes:

The second controller determines a third controller corresponding to the target data according to the address information of the target data; sends a prefetch command to the third controller, and the prefetch command includes the address of the target data information;

The third controller reads the target data into the cache of the third controller according to the address information of the target data.

The second aspect of the embodiment of the present invention provides a storage system, including:

The first controller is configured to receive a read data request sent by a host, where the read data request carries address information; determine a second controller according to the address information carried in the read data request; and send the address information to the second controller ;

The second controller is configured to obtain address information of target data to be read according to the address information, so as to read the target data into the cache according to the address information of the target data.

In the first implementation manner of the second aspect of the embodiments of the present invention, the address information carried in the read data request includes the start address carried in the read data request;

The first controller is specifically configured to determine the second controller according to the start address carried in the read data request and according to a set hash algorithm.

With reference to the first implementation manner of the second aspect of the embodiments of the present invention, in the second implementation manner of the second aspect of the embodiments of the present invention, the set hash algorithm includes a consistent hash algorithm.

In the third implementation manner of the second aspect of the embodiments of the present invention, the address information carried in the read data request includes the start address carried in the read data request;

The first controller is specifically configured to query a preset configuration table according to the start address to obtain a second controller corresponding to the start address.

In the fourth implementation manner of the second aspect of the embodiments of the present invention, the second controller is further configured to read the target data into the cache of the second controller according to the address information of the target data .

In the fifth implementation manner of the second aspect of the embodiments of the present invention, the system further includes a third controller;

The second controller is further configured to determine a third controller corresponding to the target data according to the address information of the target data; and send a prefetch command to the third controller, and the prefetch command includes the target address information of the data;

The third controller is configured to read the target data into the cache of the third controller according to the address information of the target data.

In the embodiment of the present invention, after the first controller receives the read data request sent by the host, it determines the second controller according to the address information carried in the read data request, and sends the address information to the second controller. The controller is configured to obtain the target data to be read by the second controller according to the address information, so as to execute the operation of reading the target data into the cache. Since the controller that executes the operation to obtain the target data to be read is determined by the address information carried in the read data request, the read data request that occurs on a logical address can be centrally analyzed by a controller. For this logical address In other words, the obtained read data request information is comprehensive, so the target data to be read can be accurately predicted and read into the cache.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are For some embodiments of the present invention, those skilled in the art can also obtain other drawings based on these drawings without any creative work.

FIG. 1 is a schematic diagram of an application network architecture of a method for caching data provided by an embodiment of the present invention;

FIG. 2 is a flow chart of a method for caching data provided by an embodiment of the present invention;

FIG. 3 is a flowchart of another method for caching data provided by an embodiment of the present invention;

FIG. 4 is a data structure diagram of a data prefetching unit provided by an embodiment of the present invention;

5 is a data structure diagram of a data block table in a data prefetching unit provided by an embodiment of the present invention;

FIG. 6 is a schematic flowchart of another method for caching data provided by an embodiment of the present invention;

FIG. 7 is a schematic diagram of the correspondence between a read data request and a data block provided by an embodiment of the present invention;

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

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

System architecture of the embodiment of the present invention

The method for caching data provided by the embodiments of the present invention can be implemented on a storage system. FIG. 1 is a schematic diagram of a system architecture of a method for caching data provided by an embodiment of the present invention. As shown in FIG. 1 , the storage system includes multiple controllers (four controllers are taken as an example in the figure) and storage devices. In this embodiment, the storage device is described by taking a hard disk as an example.

FIG. 1 is only an illustration, and does not limit a specific networking mode, for example, cascading tree networking and ring networking are all possible. As long as the controller and the storage device can communicate with each other.

The controller may include any computing device known in the art, such as servers, desktop computers, and the like. In an application scenario of the embodiment of the present invention, each controller can process the read data request from the host, and can also access the data stored in the storage device, such as reading the data in the storage device and storing it in the in the cache. Or, in another application scenario, each controller can handle read data requests from the host, but each controller corresponds to a section of storage space in the storage device (such as a part of the disk or a part of the storage space of a disk), That is to say, each segment of storage space in the storage device has its corresponding specific controller and cannot be managed or accessed by other controllers. It should be noted that the storage device here refers to a magnetic disk, hard disk or other storage media, excluding a controller.

Inside the controller, there is a cache (cache). The cache is a buffer memory between the CPU and the hard disk. It is smaller than the hard disk but faster than the hard disk. Some data is stored in the cache. When the CPU is processing a read data request, if the available data is found in the cache, it is a cache hit.

Each controller can communicate with each other and can access the data stored in the cache of other controllers. For example, when controller 0 receives a data read request from a host (not shown in the figure) to access data A, data A is not stored in the cache of controller 0, but data A is stored in the cache of controller 1, so the controller 0 can send a data read command to controller 1, so that controller 1 reads data A from the cache and sends it to controller 0, so controller 0 can directly return data A to the host. It should be noted that since the data communication between caches adopts high-speed data transmission channels, the cache data sharing and access speed between controllers is very fast. The process of obtaining data in the server's cache takes a very short time.

An operating system and other software programs are installed on the controller. For example, each controller includes at least one prefetch management unit, and in the embodiment of the present invention, the number of prefetch management units included in each controller is approximately equal. Each prefetching management unit is used to perform a logical storage space data read operation of a range of addresses. The logical storage space managed by each prefetch management unit here can be a logical storage unit (Logic Unit Number, LUN), or a section of a LUN, or a folder, etc., which is not limited here. The distribution of the prefetching management units in the controller can be determined according to the address range of the logical storage space. For example, for a logical address (such as Logic Block Address, LBA), the controller where the prefetch management unit corresponding to the logical address is located can be obtained according to a consistent hash algorithm or other hash algorithms.

The storage device may include a storage device known in the current technology, such as an SSD, or a direct access storage device (Direct Access Storage Device, DASD). The storage space of the storage device can be divided into several logical blocks (chunk), and each chunk has a unique ID. In this embodiment, data in the storage device is managed in units of chunks, for example, data may be read into the cache in units of chunks.

According to the foregoing description, in an application scenario of the embodiment of the present invention, each controller can perform read and write operations on the storage device, for example, each controller can read the data in the storage device to its own In the cache, the cache hit can be achieved when executing subsequent read data requests; in another application scenario, each controller corresponds to a part of the storage space of the storage device, and can only read the data stored in this part of the storage space. A write operation, such as reading the data stored in this part of the storage space into its own cache, while the data stored in other storage spaces of the storage device are managed by other controllers.

How to cache data

The method for caching data provided by the embodiment of the present invention is introduced below. As shown in FIG. 2 , it is a flow chart of the method for caching data provided by the embodiment of the present invention. controllers, wherein each controller includes a cache; the method includes:

Step S201: the first controller receives the read data request sent by the host, the read data request carries address information; determines the second controller according to the address information carried in the read data request; sends the second controller to the second controller Address information.

Optionally, the address information includes the start address and length of the data to be read, and the second control corresponding to the read data request can be obtained according to the start address of the data to be read and according to a set hash algorithm. device.

Step S202: The second controller obtains address information of the target data to be read according to the address information, so as to read the target data into the cache according to the address information of the target data.

Optionally, after the second controller obtains the address information of the target data to be read according to the address information, it may read the target data into the cache of the second controller according to the address information of the target data; Or send a prefetch command to the third controller according to the address information of the target data, and the third controller reads the target data into the cache of the third controller according to the address information of the target data.

Optionally, this embodiment of the present invention can also be applied in a distributed system, the distributed system includes multiple nodes, each node is a server, and each server performs a function similar to that of each controller in the storage system , which will not be repeated here.

It should be noted that the first controller may receive one or more read data requests sent by the host. When there are multiple read data requests, it can be judged whether the multiple read data requests are continuous according to the address information carried by the multiple read data requests, and if they are continuous, the multiple read data requests can be combined to obtain A continuous piece of address information. The determining the second controller according to the address information carried in the read data request specifically refers to determining the second controller according to the combined continuous address information. If the multiple read data requests are discontinuous, the second controller is determined respectively according to the address information carried in each read data request.

In the embodiment of the present invention, after the first controller receives the read data request sent by the host, it determines the second controller according to the address information carried in the read data request, and sends the address information to the second controller. The controller is configured to obtain the target data to be read by the second controller according to the address information, so as to execute the operation of reading the target data into the cache. Since the controller that executes the operation to obtain the target data to be read is determined by the address information carried in the read data request, the read data request that occurs on a logical address can be centrally analyzed by a controller. For this logical address In other words, the obtained read data request information is comprehensive, so the target data to be read can be accurately predicted and read into the cache.

As shown in FIG. 3 , it is a flow chart of another method for caching data provided by the embodiment of the present invention. For convenience of description, the embodiment of the present invention takes three controllers as an example, but it is not limited to three controllers in fact. Referring to Fig. 3, it may be the processor in the controller that specifically performs the following steps, and the method includes:

Step S301: The first controller receives the first read data request sent by the host, the first read data request carries the address information of the first data to be read, wherein the address information includes the start of the first data to be read address (LBA) and length.

It should be noted that the logical address in the embodiment of the present invention is also called the start address, also called the LBA.

Step S302: the first controller determines the controller corresponding to the first data read request.

In the embodiment of the present invention, each controller includes at least one prefetch management unit. In the embodiment of the present invention, the number of prefetch management units included in each controller is approximately equal, and each prefetch The management unit is used to manage the storage space of a certain address range, such as a certain area of a LUN. Specifically, the controller corresponding to the first read data request can be obtained according to the LBA of the first data to be read according to the consistent hash algorithm or other hash algorithms, and then the prefetch management unit in the controller can be obtained. When the controller contains a prefetch management unit, the controller corresponding to the first read data request is determined, then the prefetch management unit corresponding to the first read data request is also determined; when the controller contains multiple prefetch When using a management unit, each prefetch management unit manages a storage space of an address range, so a prefetch management unit in a controller can also be uniquely determined according to the LBA. For example, the controller corresponding to the first data to be read is the second controller.

Hash algorithm, also known as hash algorithm, refers to a data structure that determines a unique access address based on a certain key (key) value, and its purpose is to speed up the search. Among them, key refers to the starting address. Optionally, a common hash algorithm can be implemented with a hash table, and the corresponding access address can be obtained by searching in the hash table according to the key value. It should be noted that the general hash algorithm is a linear calculation method. In the embodiment of the present invention, a hash algorithm may be used to uniquely determine a controller through the input of the start address.

Optionally, the consistent hash algorithm can use a ring data structure to locate the key value to the access location. The ring data structure may contain multiple virtual nodes, such as virtual node 0, virtual node 1, virtual node 2, virtual node 3...virtual node 10, and each virtual node corresponds to a segment of access address. Wherein every two adjacent virtual nodes are connected sequentially, and virtual node 10 is connected end-to-end with virtual node 0 to form a ring together. Take the storage system with three controllers as an example. The three controllers are respectively named controller A, controller B, and controller C. Each controller corresponds to several virtual nodes in the ring data structure. For example, controller A corresponds to Virtual node 0, virtual node 1, virtual node 2, and virtual node 3; controller B corresponds to virtual node 4, virtual node 5, virtual node 6, and virtual node 7; controller C corresponds to virtual node 8, virtual node 9, and virtual node 10. In this way, the start address can also uniquely correspond to a controller.

However, for the consistent hash algorithm, when a new controller is added to the storage system, for example, controller D is added, there is no need to rearrange the data structure or modify the algorithm, and only need to adjust the corresponding virtual node of each controller. Make the newly added controller D correspond to a section of starting address.

Optionally, each controller of the storage system can store a preset configuration table, the configuration table includes the corresponding relationship between the start address and each controller, and the controller that receives the read data request can according to The start address carried in the read data request is queried in the configuration table, so as to obtain the controller corresponding to the start address.

Optionally, the above-mentioned configuration table may only be stored in one controller, and when other controllers receive a read data request, they may send a query request to the controller storing the configuration table, and the query request includes the start address, so that the controller that saves the configuration table can query in the configuration table according to the start address, so as to obtain the controller corresponding to the start address, and send the query result to the The requested controller.

Optionally, in order to prevent the configuration table from being lost when the controller storing the configuration table fails, another controller of the storage system may store a copy of the configuration table.

Optionally, the controller corresponding to the start address can also be obtained by taking a modulus. Specifically, the start address is divided by the number of controllers, and the corresponding control can be obtained according to the calculated modulus. device.

Step S303: The second controller receives the second read data request sent by the host, the second read data request carries the address information of the second data to be read, wherein the address information includes the start of the second data to be read address (LBA) and length.

It should be noted that there is no sequence between step S301 and step S303.

Step S304: the second controller determines the controller corresponding to the second data read request.

Specifically, the corresponding controller may be obtained according to the LBA of the second data to be read, which is similar to step S302 and will not be repeated here.

When the controllers corresponding to the first data read request are different from the controllers corresponding to the second data read request, the two controllers may respectively perform cache data prefetch operations without affecting each other. The discussion here focuses on the case that the controller corresponding to the first data read request is the same as the controller corresponding to the second data read request.

Step S305: The first controller sends the drop point information of the first read data request to the second controller, the drop point information includes the address information of the first data to be read, and the drop point information may also include sending the first The ID of the host that reads the data request, the ID of the first controller, etc., and the drop point information can be used as an analysis basis for data prefetching.

Since the controller corresponding to the second read data request is the second controller, the processor of the second controller can push the address where the landing point information of the second read data request is stored in the cache to the prefetch of the second controller The management unit, or the prefetch management unit of the second controller obtains the landing point information of the second data read request in other ways, which is not limited herein.

Step S306: The second controller predicts the target data of the next data read request according to the drop point information of the first read data request and the drop point information of the second read data request.

The next read data request refers to the read data request to be received by the storage system (not yet received), for the convenience of description, the next read data request is referred to as the third read data request. It should be noted that the next read data request is not limited to the read data request following the first read data request and the second read data request, as long as it is the read data received after the first read data request and the second read data request Each request can be referred to as the next read data request.

The second controller may use the prefetch management unit to predict target data of the third read data request. The prefetch management unit is a functional unit included in the controller for performing cache data read operations. As shown in FIG. 4 , the prefetch management unit includes: a data block table, an interface, and a prefetch strategy module. The data block table includes multiple data blocks, each data block corresponds to a logical block (chunk) on the disk, and has the same size. The data block is used to record drop point information of the data read request and other information. The data block table may be sorted according to the LBAs contained in the drop point information from small to large, or from large to small. In addition, the data block table in the embodiment of the present invention may not be limited to the form of a table, and may also be a red-black tree, or a binary tree or other data management structures that can implement sequential search. It should be noted that what is recorded in each data block is the location information of the read data request and other information, but does not include the data to be read itself. In addition, the interface is used to receive the landing point information of the read data request sent by other controllers, or send a prefetch command to other controllers; the prefetch strategy module is used to execute the read operation according to the set prefetch strategy.

As shown in Figure 5, the information recorded in each data block can include: Chunk ID, drop point information, and the ID of the chunk read last time, wherein the drop point information can specifically include host ID, controller ID, LBA and length;

The Chunk ID specifically refers to the ID of the chunk on the disk corresponding to the data block, and the initial address of the chunk can be obtained by multiplying the Chunk ID by the size of each chunk. Since data is prefetched in units of chunks, it is also necessary to know the start address of the chunk where the target data is located when prefetching the target data. It should be noted that the LBA described above refers to the start address of the read data request, which is different from the start address of the chunk. In some cases, the start address of the read data request is the same as the start address of the chunk, but in most cases, the start address of the read data request is not the same as the start address of the chunk.

The ID of the chunk read last time is used to identify the prefetch range of the last read operation that occurred on the data block, since the read operation is performed in units of chunks Therefore, it can be judged according to the ID of the chunk read last time whether this prefetching overlaps with the range of the last prefetching, and if so, the overlapping chunks may not be included when performing the read operation.

In addition, the sequence number, time stamp, bitmap and other information of the read data request can also be recorded.

As shown in FIG. 6, step S306 may specifically include the following steps:

S3061: According to the drop point information of the first read data request and the drop point information of the second read data request, determine that the first read data request and the second read data request have a continuous sequence relationship.

The specific judgment method is to obtain the end address of the first read data request according to the start address and length of the first read data request, if the end address of the first read data request is continuous with the start address of the second read data request, then Explain that the first read data request and the second read data request have a continuous sequential relationship; or, obtain the end address of the second read data request according to the start address and length of the second read data request, if the end of the second read data request If the address is continuous with the start address of the first read data request, it means that the first read data request and the second read data request have a continuous sequence relationship.

It should be noted that, in the embodiment of the present invention, the first read data request and the second read data request may not be absolutely continuous, and a certain degree of address gap is allowed between them.

S3062: Determine data blocks corresponding to the first data read request and the second data read request.

Specifically, the data blocks corresponding to the first data read request and the second data read request may be determined according to the drop point information of the first data read request and the drop point information of the second data read request. Since the first read data request and the second read data request have a sequential relationship, their corresponding data blocks are also continuous. Data blocks corresponding to the first read data request and the second read data request may be as shown in FIG. 7 .

S3063: Determine data blocks that are continuous with the data blocks corresponding to the first read data request and the second read data request, and obtain the largest continuous segment of the data block.

Specifically, the data block table may be traversed forward according to the data blocks corresponding to the first read data request and the second read data request, if there is a data block corresponding to the first read data request and the second read data request If it is continuous, judge whether the read data request on the data block that occurred last time is continuous with the current first read data request and the second read data request according to the drop point information recorded on the continuous data block. If continuous, continue Continuous data blocks are obtained in the data block table until the maximum continuous segment of the data block corresponding to the first read data request and the second read data request is obtained.

S3064: Obtain the length and start address of the target data.

Specifically, the length of the target data can be obtained through the calculation of the prefetching strategy according to the size of the largest continuous segment of the data block obtained in step S3063.

Optionally, if it is known from the last read chunk ID that part of the target data has been prefetched during the last read operation, then this part of data may be removed.

In addition, to predict the target data of the next read data request, in addition to determining the length of the target data, it is also necessary to determine the start address of the target data. In this embodiment, the start address of the target data is the end address of the first data read request or the end address of the second data read request.

After the second controller predicts the target data of the next read data request, the target data can be read from the disk according to the start address and length of the target data, stored in the cache of the second controller, and It can be used for a cache hit when the third read data request is executed next time. This situation is mainly applicable to a scenario where each controller can manage or access each disk in the storage device.

However, in some application scenarios, each controller can only manage or access part of the storage space in the storage device (part of the disk or part of the storage space of a disk), that is to say, each segment of storage space in the storage device has Its corresponding specific controller cannot be managed or accessed by other controllers. In this case, assuming that the storage space where the target data is located is managed by the third controller, this embodiment may further include:

Step S307: the second controller sends a prefetch command to the third controller, the prefetch command includes the start address and length of the target data, so that the third controller reads the target data into its cache.

Optionally, the second controller may determine according to the start address of the target data that the storage space where the target data is located is managed by the third controller, and therefore may send a data prefetch command to the third controller. Specifically, the second controller may obtain the controller corresponding to the storage space where the target data is located from the start address of the target data through system configuration or some existing calculation methods.

Step S308: the third controller prefetches the target data into its cache.

Specifically, the third controller may read the target data from the disk according to the start address and length of the target data, and store it in the cache of the third controller.

Step S309: the first controller receives a third data read request sent by the host, and the data to be read in the third data read request is the target data, or the data to be read is a part of the target data.

After the first controller receives the third data read request, it finds that the target data is not stored in its cache, but the target data is stored in the cache of the third controller, and step S310 is executed.

Optionally, it may be any controller in the storage system that receives the third read data request. If the third controller receives the third read data request, the third controller may directly cache the The target data is sent to the host without performing steps S310-S311; if other controllers in the storage system receive the third read data request, the operation steps are the same as those of the first controller receiving the third read data Requests are similar.

Step S310: the first controller sends a data read command to the third controller, the data read command includes the start address and length of the target data, and is used to request the third controller to send the target data .

Step S311: the third controller sends the target data to the first controller.

It should be noted that the data channel between the controllers uses a high-speed data transmission channel. According to statistics, the access speed of cache data between the controllers is generally less than 1ms. However, if there is no cache hit, the speed of reading the target data from the disk is 6-10ms. Therefore, even cross-controller hits are much faster than reading data from disk.

Step S312: After receiving the target data sent by the third controller, the first controller sends the target data to the host, that is, a cache hit is achieved.

In addition, in this embodiment, the first controller may also determine the controller corresponding to the third data read request according to the information carried in the third data read request, and send the landing point information of the third data read request to the controller, so that The prefetch management unit of the controller continues to predict the data to be read in the next data read request, and executes the operation of caching the data. This process can repeat step S301-step S308, which will not be repeated here.

In the embodiment of the present invention, after the first controller receives the read data request sent by the host, it determines the second controller according to the address information carried in the read data request, and sends the address information to the second controller. The controller is configured to obtain the target data to be read by the second controller according to the address information, so as to execute the operation of reading the target data into the cache. Since the controller that executes the operation to obtain the target data to be read is determined by the address information carried in the read data request, the read data request that occurs on a logical address can be centrally analyzed by a controller. For this logical address In other words, the obtained read data request information is comprehensive, so the target data to be read can be accurately predicted and read into the cache.

Storage System

The following describes the storage system provided by the embodiment of the present invention. As shown in FIG. 8 , it is a structural diagram of the storage system 80 provided by the embodiment of the present invention, including multiple controllers, wherein each controller includes a processor and a cache; wherein :

The first controller 801 is configured to receive the read data request sent by the host, and the read data request carries address information; determine the second controller 802 according to the address information carried in the read data request; and send the request to the second controller 802 The address information. Specifically, it is the processor in the first controller 801 that performs the above operations.

Optionally, the address information includes the start address and length of the data to be read, and the controller corresponding to the read data request can be obtained according to the start address of the data to be read according to a set hash algorithm. The second controller 802 .

In the embodiment of the present invention, each controller includes at least one prefetch management unit. In the embodiment of the present invention, the number of prefetch management units included in each controller is approximately equal, and each prefetch The management unit is used to manage the storage space of a certain address range, such as a certain area of a LUN. Specifically, the controller corresponding to the first read data request can be obtained according to the LBA of the first data to be read according to the consistent hash algorithm or other hash algorithms, and then the prefetch management unit in the controller can be obtained. When the controller contains a prefetch management unit, the controller corresponding to the first read data request is determined, then the prefetch management unit corresponding to the first read data request is also determined; when the controller contains multiple prefetch When using a management unit, each prefetch management unit manages a storage space of an address range, so a prefetch management unit in a controller can also be uniquely determined according to the LBA. For example, the controller corresponding to the first data to be read is the second controller.

Optionally, a hash algorithm may be used to uniquely determine a controller through the input of the start address, and the hash algorithm may be a consistent hash algorithm.

Optionally, each controller of the storage system can store a preset configuration table, the configuration table includes the corresponding relationship between the start address and each controller, and the controller that receives the read data request can according to The start address carried in the read data request is queried in the configuration table, so as to obtain the controller corresponding to the start address.

Optionally, the above-mentioned configuration table may only be stored in one controller, and when other controllers receive a read data request, they may send a query request to the controller storing the configuration table, and the query request includes the start address, so that the controller that saves the configuration table can query in the configuration table according to the start address, so as to obtain the controller corresponding to the start address, and send the query result to the The requested controller.

Optionally, in order to prevent the configuration table from being lost when the controller storing the configuration table fails, another controller of the storage system may store a copy of the configuration table.

Optionally, the controller corresponding to the start address can also be obtained by taking a modulus. Specifically, the start address is divided by the number of controllers, and the corresponding control can be obtained according to the calculated modulus. device.

After the first controller 801 determines the second controller 802 according to the address information carried in the read data request, it may send the address information to the second controller 802 .

The second controller 802 is configured to obtain address information of target data to be read according to the address information, so as to read the target data into the cache according to the address information of the target data. Specifically, it is the processor in the first controller 801 that performs the above operations.

Optionally, after the second controller 802 obtains the address information of the target data to be read according to the address information, it may read the target data into the cache of the second controller 802 according to the address information of the target data or send a prefetch command to the third controller 803 according to the address information of the target data, and the third controller 803 reads the target data into the cache of the third controller 803 according to the address information of the target data middle.

Wherein, the second controller 802 may use the prefetch management unit to obtain target data to be read. The specific obtaining method is similar to the method embodiment described above, and will not be repeated here.

Optionally, the first controller 801 receives the next read data request sent by the host, and the data to be read in the next read data request is the target data, or the data to be read is a part of the target data. After the first controller 801 receives the next read data request, it finds that the target data is not stored in its cache, but the target data is stored in the cache of the third controller 803, then it can send the request to the third controller 803 Sending a data read command, where the data read command includes the start address and length of the target data, and is used to request the third controller 803 to send the target data. After receiving the data read command, the third controller 803 sends the target data to the first controller 801 .

It should be noted that the next read data request is not limited to the read data request received immediately after the first controller, and any read data request received after the read data request can be referred to as the next read data request.

Since the data channel between controllers uses a high-speed data transmission channel, according to statistics, the access speed of cache data between controllers is generally less than 1ms. However, if there is no cache hit, the speed of reading the target data from the disk is 6-10ms. Therefore, even cross-controller hits are much faster than reading data from disk.

In the embodiment of the present invention, after the first controller receives the read data request sent by the host, it determines the second controller according to the address information carried in the read data request, and sends the address information to the second controller. The controller is configured to obtain the target data to be read by the second controller according to the address information, so as to execute the operation of reading the target data into the cache. Since the controller that executes the operation to obtain the target data to be read is determined by the address information carried in the read data request, the read data request that occurs on a logical address can be centrally analyzed by a controller. For this logical address In other words, the obtained read data request information is comprehensive, so the target data to be read can be accurately predicted and read into the cache.

Those of ordinary skill in the art will understand that various aspects of the present invention, or possible implementations of various aspects, may be embodied as systems, methods or computer program products. Accordingly, aspects of the present invention, or possible implementations of various aspects, may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, etc.), or an embodiment combining software and hardware aspects, described in These are collectively referred to herein as "circuits," "modules," or "systems." In addition, aspects of the present invention, or possible implementations of various aspects, may take the form of computer program products, and computer program products refer to computer-readable program codes stored in computer-readable media.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. Computer-readable storage media include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or devices, or any suitable combination of the foregoing, such as random access memory (RAM), read-only memory (ROM), Erase Programmable Read-Only Memory (EPROM or Flash), Fiber Optic, Portable Read-Only Memory (CD-ROM).

The processor in the computer reads the computer-readable program code stored in the computer-readable medium, so that the processor can execute the functional actions specified in each step in the flow chart, or a combination of steps; A device that performs functional actions specified in each block or a combination of blocks.

The computer readable program code may execute entirely on the user's computer, partly on the user's computer, as a separate software package, partly on the user's computer and partly on a remote computer, or entirely on the remote computer or server . It should also be noted that, in some alternative implementations, the functions noted at the steps in the flowcharts or blocks in the block diagrams may occur out of the order noted in the figures. For example, two steps, or two blocks shown in succession, may in fact be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

Claims (12)

1. a data cached method, described method is applied in storage system, and described storage system comprises multiple controller, and wherein, each controller comprises buffer memory; It is characterized in that, described method comprises:

The read data request that first controller Receiving Host sends, described read data request carries address information; According to the address information determination second controller that described read data request is carried; Described address information is sent to described second controller;

Described second controller obtains the address information of target data to be read according to described address information, determines according to the address information of described target data the 3rd controller that described target data is corresponding; Send prefetched command to described 3rd controller, described prefetched command comprises the address information of described target data;

Described target data reads in the buffer memory of described 3rd controller according to the address information of described target data by described 3rd controller.

2. method according to claim 1, is characterized in that, the address information that described read data request is carried comprises the start address that described read data request is carried;

The described address information determination second controller carried according to described read data request comprises:

According to the start address that described read data request is carried, according to the hashing algorithm of setting, determine second controller.

3. method according to claim 2, is characterized in that, the hashing algorithm of described setting comprises consistance hash algorithm.

4. method according to claim 1, is characterized in that, the address information that described read data request is carried comprises the start address that described read data request is carried;

The described address information determination second controller carried according to described read data request comprises:

According to the allocation list that described start address inquiry is preset, obtain the second controller that described start address is corresponding.

5. method according to claim 1, is characterized in that, also comprises:

Described first controller receives the next read data request that described main frame sends, and described next read data request comprises the address information of described target data;

Determine according to the address information of described target data to store described target data in the buffer memory of described 3rd controller;

Send data read command to described 3rd controller, make described 3rd controller that described target data is sent to described first controller;

Described target data is sent to described main frame.

6. method according to claim 1, is characterized in that, the address information of described target data comprises start address and the length of described target data;

The address information that described second controller obtains target data to be read according to described address information comprises:

The address information that described second controller carries according to the read data request that described main frame sends, determines the start address of described target data; And

The address information that the read data request sent according to described main frame is carried, determines the first data block corresponding in data block table, and with described first data block continuous print second data block; According to the summation of the size of described first data block and the second data block, obtain the length of described target data.

7. a storage system, is characterized in that, described system comprises:

First controller is used for the read data request that Receiving Host sends, and described read data request carries address information; According to the address information determination second controller that described read data request is carried; Described address information is sent to described second controller;

Described second controller is used for the address information obtaining target data to be read according to described address information, determines according to the address information of described target data the 3rd controller that described target data is corresponding; Send prefetched command to described 3rd controller, described prefetched command comprises the address information of described target data;

Described target data reads in the buffer memory of described 3rd controller according to the address information of described target data by described 3rd controller.

8. system according to claim 7, is characterized in that, the address information that described read data request is carried comprises the start address that described read data request is carried;

The start address of described first controller specifically for carrying according to described read data request, according to the hashing algorithm of setting, determines second controller.

9. system according to claim 8, is characterized in that, the hashing algorithm of described setting comprises consistance hash algorithm.

10. system according to claim 7, is characterized in that, the address information that described read data request is carried comprises the start address that described read data request is carried;

Described first controller, specifically for the allocation list preset according to described start address inquiry, obtains the second controller that described start address is corresponding.

11. systems according to claim 7, is characterized in that,

Described first controller is also for receiving the next read data request that described main frame sends, and described next read data request comprises the address information of described target data;

Determine according to the address information of described target data to store described target data in the buffer memory of described 3rd controller;

Send data read command to described 3rd controller, make described 3rd controller that described target data is sent to described first controller;

Described target data is sent to described main frame.

12. systems according to claim 7, is characterized in that, the address information of described target data comprises start address and the length of described target data;

The address information that the read data request that described second controller is used for sending according to described main frame is carried, determines the start address of described target data; And

The address information that the read data request sent according to described main frame is carried, determines the first data block corresponding in data block table, and with described first data block continuous print second data block; According to the summation of the size of described first data block and the second data block, obtain the length of described target data.