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File Access and Protocols Feature Guide 13

OceanStor 18500 V3 and 18800 V3 Mission Critical Storage System V300R003

This document describes the implementation principles and application scenarios of the NAS feature. Also, it explains how to configure and manage NAS.
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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Overview

Overview

NFS is a protocol developed by Sun. Internet Engineering Task Force (IETF) is in charge of developing its new versions. This protocol is designed for file sharing among Linux and UNIX operating systems.

NFS works based on client/server architecture. The server provides other computers with file system access, whereas the client accesses the shared file system. The NFS feature enables clients running a variety of operating systems to share files over a network.

The OceanStor 18500 V3/18800 V3 supports the NFS protocol, enabling users to flexibly and easily use clients and configure desired environments. When being configured as an NFS server, the storage system provides shared file system access for clients that use NFS v3 and NFS v4. NFS allows users to centrally store data in the storage system. With NFS, users can access remote file systems in the same way as accessing local files over a network, reducing local disk space required.
NOTE:
During online upgrade, NFS v4 cannot ensure service continuity due to the limitation of its own protocol mechanism, but NFS v3 can ensure service continuity.
NFS highlights:
  • High concurrency

    Multiple clients can use the same file so that all the users can access the same data.

  • Data integrity

    All users can read the same group of files.

  • Ease-of-use

    File system mounting and remote file system access are transparent to users.

NFS Lock Policy

The file lock policy is a file read and write mechanism, and is used to ensure data consistency. When clients of different protocols operate on the same file or directory, file locks ensure that the data does not conflict. The NFS mechanism includes advisory and mandatory locks. By default, mandatory locks are enabled. You are advised to use advisory locks when the requirements for read and write performance are high and clients of different protocols do not access the same file or directory at the same time. If clients of different protocols simultaneously access the same file or directory, mandatory locks are recommended.

  • The file lock policy is a file read and write mechanism, and is used to ensure data consistency. When clients of different protocols operate on the same file or directory, file locks ensure that the data does not conflict.
  • Mandatory locks are used for the kernel. When a client accesses a file, the kernel checks whether the file is configured with mandatory locks. If mandatory locks are set, the client cannot perform operations on the file. The kernel confines operations of the client.
NFS lock policies can be set both on the clients and the servers.
  • If mandatory NFS lock policies are set on the clients, conflicts are less likely to occur when multiple client processes access the same file. If advisory NFS lock policies are set on the clients, conflicts may occur when clients of different protocols access the same file or directory.
  • If mandatory NFS lock policies are set on the servers, conflicts are less likely to occur when multiple client processes access the same file or directory. If advisory NFS lock policies are set on the servers, conflicts may occur when clients of different protocols access the same file or directory.
The NFS client supports advisory locks by default. The SMB client and the server support mandatory locks by default. Since the NFS lock policy can be set on both the clients and servers, the file NFS lock policy depends on the settings of lock policies on the clients and the servers, as shown in Table 2-1.
Table 2-1  NFS Lock Policies of Files

NFS lock policy of clients

NFS lock policy of servers

NFS lock policy of files

Mandatory lock

Advisory lock

Mandatory lock

Mandatory lock

Mandatory lock

Mandatory lock

Advisory lock

Mandatory lock

Mandatory lock

Advisory lock

Advisory lock

Advisory lock

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Updated: 2019-08-14

Document ID: EDOC1000084098

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