CN111708734A

CN111708734A - Metadata access method, system, device and medium for distributed system

Info

Publication number: CN111708734A
Application number: CN202010475904.5A
Authority: CN
Inventors: 罗浩; 李雪生; 李�杰
Original assignee: Suzhou Inspur Intelligent Technology Co Ltd
Current assignee: Suzhou Inspur Intelligent Technology Co Ltd
Priority date: 2020-05-29
Filing date: 2020-05-29
Publication date: 2020-09-25

Abstract

The invention discloses a metadata access method of a distributed system, which comprises the following steps: responding to a metadata access request initiated by a client, and judging whether the client caches metadata or not; responding to the metadata cached in the client, and judging whether the metadata is marked as invalid or not; in response to the metadata being marked as invalid, re-initiating a metadata access request to a metadata server; judging whether the metadata in the cache of the metadata server is marked as invalid or not; in response to the metadata in the cache of the metadata server being marked as stale, the metadata is retrieved from a metadata disk of the metadata server and cached. The invention also discloses a system, a computer device and a readable storage medium. The scheme provided by the invention realizes the metadata synchronization between the client and the metadata server by judging whether the metadata in the cache is marked as invalid or not and acquiring the actual metadata in the metadata disk if the metadata is invalid.

Description

Metadata access method, system, device and medium for distributed system

Technical Field

The present invention relates to the field of distributed systems, and in particular, to a method, a system, a device, and a storage medium for accessing metadata of a distributed system.

Background

With the generation of massive data, the storage and access performance of the data is higher and higher. In the distributed file system, metadata access is a necessary path of a data access process, and in all accesses, the access of metadata accounts for more than 50%, so that the improvement of the performance of metadata access is particularly important. Metadata access performance can be improved by implementing client-side local caching techniques. However, ensuring consistency of the client metadata cache with metadata preservation on the MDS is one of the key technologies. Therefore, self-detection on the distributed storage is particularly important, and the problem that the metadata of the distributed system is not synchronous under abnormal conditions such as network disconnection, recovery and the like is solved.

Disclosure of Invention

In view of the above, in order to overcome at least one aspect of the above problems, an embodiment of the present invention provides a metadata access method for a distributed system, including the following steps:

responding to a metadata access request initiated by a client, and judging whether the metadata is cached by the client;

responding to the client cache with the metadata, and judging whether the metadata is marked as invalid;

re-initiating a metadata access request to a metadata server in response to the metadata being marked as stale;

determining whether the metadata in the cache of the metadata server is marked as stale;

in response to the metadata in the cache of the metadata server being marked as stale, retrieving and caching the metadata from a metadata disk of the metadata server.

In some embodiments, further comprising:

and updating the metadata acquired from the metadata disk of the metadata server into the cache of the metadata server and/or the cache of the client.

In some embodiments, further comprising:

verifying the metadata in the cache of the metadata server and the metadata cached by the client at intervals of a preset time period;

in response to the failure to verify, marking both the metadata in the cache of the metadata server and the metadata cached by the client as stale.

In some embodiments, checking the metadata in the cache of the metadata server and the metadata cached by the client at intervals of a preset time period further includes:

responding to the verification of the metadata in the cache of the metadata server and the metadata cached by the client, and acquiring the quantity of the metadata which is configured in advance and is verified at a single time;

and repeatedly acquiring the metadata of the preset quantity for many times, and checking according to the inode number and the MD5 value of the metadata until all the metadata are checked.

In some embodiments, further comprising:

in response to the metadata not being marked as stale, directly accessing the metadata cached by the client.

In some embodiments, further comprising:

in response to the client not caching the metadata, initiating a metadata access request to a metadata server;

in response to the metadata in the metadata server's cache not being marked as stale, returning the metadata directly from the metadata server's cache.

Based on the same inventive concept, according to another aspect of the present invention, an embodiment of the present invention further provides a metadata access system for a distributed system, including:

the first response module is configured to respond to a metadata access request initiated by a client and judge whether the metadata is cached by the client;

a second response module configured to determine whether the metadata is marked as invalid in response to the client caching the metadata;

a third response module configured to re-initiate a metadata access request to a metadata server in response to the metadata being marked as stale;

a determination module configured to determine whether the metadata in the cache of the metadata server is marked as stale;

a fourth response module configured to retrieve and cache the metadata from a metadata disk of the metadata server in response to the metadata in the cache of the metadata server being marked as stale.

In some embodiments, further comprising an update module configured to:

Based on the same inventive concept, according to another aspect of the present invention, an embodiment of the present invention further provides a computer apparatus, including:

at least one processor; and

a memory storing a computer program operable on the processor, wherein the processor executes the program to perform the steps of any of the distributed system metadata access methods described above.

Based on the same inventive concept, according to another aspect of the present invention, an embodiment of the present invention further provides a computer-readable storage medium storing a computer program which, when executed by a processor, performs the steps of the metadata access method of any one of the distributed systems as described above.

The invention has one of the following beneficial technical effects: the scheme provided by the invention realizes the metadata synchronization between the client and the metadata server by judging whether the metadata in the cache is marked as invalid or not and acquiring the actual metadata in the metadata disk if the metadata is invalid.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other embodiments can be obtained by using the drawings without creative efforts.

Fig. 1 is a schematic flowchart of a metadata access method for a distributed system according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a metadata access system of a distributed system according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a computer device provided in an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a computer-readable storage medium according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following embodiments of the present invention are described in further detail with reference to the accompanying drawings.

It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are used for distinguishing two entities with the same name but different names or different parameters, and it should be noted that "first" and "second" are merely for convenience of description and should not be construed as limitations of the embodiments of the present invention, and they are not described in any more detail in the following embodiments.

According to an aspect of the present invention, an embodiment of the present invention provides a metadata access method for a distributed system, as shown in fig. 1, which may include the steps of: s1, responding to the metadata access request initiated by the client, and judging whether the metadata is cached by the client; s2, responding to the metadata cached by the client, and judging whether the metadata is marked as invalid; s3, responding to the metadata marked as invalid, re-initiating the metadata access request to the metadata server; s4, judging whether the metadata in the cache of the metadata server is marked as invalid or not; s5, responding to the metadata marked as invalid in the cache of the metadata server, obtaining and caching the metadata from the metadata disk of the metadata server.

The MDS (metadata server) is responsible for managing and scheduling metadata on the whole storage system, including inodes, distributed locks, and the like. When a client accesses the file system storage, the client needs to interact with the MDS, and after applying for authorization, the authority distributed by the MDS and the obtained inode metadata are cached locally. And reading the metadata and the authority cache information in the subsequent client cache. It is therefore necessary to ensure consistency of the client cache with the metadata on the MDS. The scheme provided by the invention realizes the metadata synchronization between the client and the metadata server by judging whether the metadata in the cache is marked as invalid or not and acquiring the actual metadata in the metadata disk if the metadata is invalid.

In some embodiments, further comprising:

Specifically, on the distributed storage system, a metadata information inode check code is newly added, and an md5 algorithm is used to calculate a check code from the inode information on the MDS. After the client requests the MDS to obtain the inode metadata, a check code is also calculated by the md5 algorithm. And (4) opening up a new thread, comparing the check code information cached by the MDS and the client regularly. When inode metadata verification is performed regularly, the number of metadata verified at a single time is limited, and because a client needs to communicate with an MDS (data management system) end in the verification process, if too many verification results, a communication link is busy, and the interaction performance of normal services is affected. And the metadata in the client cache and the metadata in the metadata server can be in one-to-one correspondence through the uniqueness of the inode number so as to be checked through the MD5 value.

In some embodiments, further comprising:

Specifically, when the information of the MDS and the client cache check code is inconsistent due to abnormal conditions such as network breaking, recovery and the like, the client marks that the metadata is invalid, and marks that the metadata in the cache is invalid and trim. And when the next access is carried out, acquiring the metadata failure from the cache information, initiating a request to the MDS again to request correct metadata information in the MDS, and if the metadata information is in the MDS cache and the mark is failed, reading the actual metadata in the metadata disk and updating the MDS cache.

According to the scheme provided by the invention, an inode metadata information check code is newly added to an MDS and a client, an md5 algorithm is used for calculating an md5 value of cache metadata, a new thread is developed, and the check work of the metadata check code between the client and the MDS is processed at regular time. And the quantity of the verified metadata is limited at a time, configuration items can be added, and the quantity of the verified metadata can be configured. The user can adjust the checking working pressure according to the actual service size. And when the verification fails, the MDS and the client end respectively set the metadata in the cache to fail and can trim. When a client side initiates a new request, if a cache exists and the cache is not marked to be invalid, the cache metadata is directly read. And if the client cache metadata is marked to be invalid, initiating a request to the MDS, directly reading the metadata in the metadata disk by the MDS, returning the metadata to the client, and updating the MDS cache. If the client does not have the metadata cache, a request is sent to the MDS, and the MDS checks whether the cache exists and whether the cache is marked to be invalid or not. If the cache exists and the cache is not marked to be invalid, the MDS metadata cache information is directly returned. Otherwise, the metadata disk is read.

Based on the same inventive concept, according to another aspect of the present invention, an embodiment of the present invention further provides a metadata access system 400 of a distributed system, as shown in fig. 2, including:

a first response module 401, where the first response module 401 is configured to respond to a metadata access request initiated by a client, and determine whether the metadata is cached by the client;

a second response module 402, the second response module 402 configured to determine whether the metadata is marked as invalid in response to the client caching the metadata;

a third response module 403, the third response module 403 configured to reinitiate the metadata access request to the metadata server in response to the metadata being marked as invalid;

a determining module 404, wherein the determining module 404 is configured to determine whether the metadata in the cache of the metadata server is marked as invalid;

a fourth response module 405, the fourth response module 405 configured to retrieve and cache the metadata from a metadata disk of the metadata server in response to the metadata in the cache of the metadata server being marked as stale.

In some embodiments, further comprising an update module configured to:

In some embodiments, further comprising a verification module configured to:

In some embodiments, the verification module is further configured to:

In some embodiments, further comprising a fifth response module configured to:

In some embodiments, further comprising a sixth response module configured to:

in response to the metadata server's cache being populated with the metadata and not being marked as stale, returning the metadata directly from the metadata server's cache.

Based on the same inventive concept, according to another aspect of the present invention, as shown in fig. 3, an embodiment of the present invention further provides a computer apparatus 501, comprising:

at least one processor 520; and

a memory 510, the memory 510 storing a computer program 511 executable on a processor, the processor 520 when executing the program performing the steps of any of the above methods of metadata access for a distributed system.

Based on the same inventive concept, according to another aspect of the present invention, as shown in fig. 4, an embodiment of the present invention further provides a computer-readable storage medium 601, where the computer-readable storage medium 601 stores computer program instructions 610, and the computer program instructions 610, when executed by a processor, perform the steps of the metadata access method of any one of the above distributed systems.

Finally, it should be noted that, as will be understood by those skilled in the art, all or part of the processes of the methods of the above embodiments may be implemented by a computer program to instruct related hardware to implement the methods. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), a Random Access Memory (RAM), or the like. The embodiments of the computer program may achieve the same or similar effects as any of the above-described method embodiments.

In addition, the apparatuses, devices, and the like disclosed in the embodiments of the present invention may be various electronic terminal devices, such as a mobile phone, a Personal Digital Assistant (PDA), a tablet computer (PAD), a smart television, and the like, or may be a large terminal device, such as a server, and the like, and therefore the scope of protection disclosed in the embodiments of the present invention should not be limited to a specific type of apparatus, device. The client disclosed by the embodiment of the invention can be applied to any one of the electronic terminal devices in the form of electronic hardware, computer software or a combination of the electronic hardware and the computer software.

Furthermore, the method disclosed according to an embodiment of the present invention may also be implemented as a computer program executed by a CPU, and the computer program may be stored in a computer-readable storage medium. The computer program, when executed by the CPU, performs the above-described functions defined in the method disclosed in the embodiments of the present invention.

Further, the above method steps and system elements may also be implemented using a controller and a computer readable storage medium for storing a computer program for causing the controller to implement the functions of the above steps or elements.

Further, it should be appreciated that the computer-readable storage media (e.g., memory) herein can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory. By way of example, and not limitation, nonvolatile memory can include Read Only Memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM), which can act as external cache memory. By way of example and not limitation, RAM is available in a variety of forms such as synchronous RAM (DRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), and Direct Rambus RAM (DRRAM). The storage devices of the disclosed aspects are intended to comprise, without being limited to, these and other suitable types of memory.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as software or hardware depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the disclosed embodiments of the present invention.

The various illustrative logical blocks, modules, and circuits described in connection with the disclosure herein may be implemented or performed with the following components designed to perform the functions herein: a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination of these components. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP, and/or any other such configuration.

The steps of a method or algorithm described in connection with the disclosure herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more exemplary designs, the functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk, blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

The foregoing is an exemplary embodiment of the present disclosure, but it should be noted that various changes and modifications could be made herein without departing from the scope of the present disclosure as defined by the appended claims. The functions, steps and/or actions of the method claims in accordance with the disclosed embodiments described herein need not be performed in any particular order. Furthermore, although elements of the disclosed embodiments of the invention may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.

It should be understood that, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly supports the exception. It should also be understood that "and/or" as used herein is meant to include any and all possible combinations of one or more of the associated listed items.

The numbers of the embodiments disclosed in the embodiments of the present invention are merely for description, and do not represent the merits of the embodiments.

It will be understood by those skilled in the art that all or part of the steps of implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.

Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, of embodiments of the invention is limited to these examples; within the idea of an embodiment of the invention, also technical features in the above embodiment or in different embodiments may be combined and there are many other variations of the different aspects of the embodiments of the invention as described above, which are not provided in detail for the sake of brevity. Therefore, any omissions, modifications, substitutions, improvements, and the like that may be made without departing from the spirit and principles of the embodiments of the present invention are intended to be included within the scope of the embodiments of the present invention.

Claims

1. A method for accessing metadata in a distributed system, comprising the steps of:

2. The method of claim 1, further comprising:

3. The method of claim 2, further comprising:

4. The method of claim 3, wherein the checking the metadata in the cache of the metadata server and the metadata cached by the client is performed every preset period of time, further comprising:

5. The method of claim 1, further comprising:

6. The method of claim 1, further comprising:

7. A metadata access system for a distributed system, comprising:

8. The system of claim 7, further comprising an update module configured to:

9. A computer device, comprising:

at least one processor; and

memory storing a computer program operable on the processor, characterized in that the processor executes the program to perform the steps of the method according to any of claims 1-6.

10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, is adapted to carry out the steps of the method according to any one of claims 1-6.