Working principle and example analysis of Linux NFS mechanism

What is NFS?

network file system

A method or mechanism for storing and organizing files over a network.

Why use NFS?

All front-end application servers receive pictures, files, and videos uploaded by users and put them into the back-end storage.

The advantages of shared storage: convenient data search and retrieval; the disadvantages: high pressure on the storage server, and all data will be lost if it fails.

How NFS works

NFS functions have many services, each of which has its own port and changes frequently.

When the client looks for these ports, it needs an intermediary - the RPC service (default port number 111).

Workflow:

1. Start the RPC service

2. Start the NFS service (and register the startup port with the RPC service)

3. The client requests NFS service from RPC

4.RPC return port to the client

5. The client uses the returned port address to request NFS to transfer data.

Install NFS Service

Installation: yum install nfs-utils rpcbind

View: rpm -qa nfs-utils rpcbind

Start the service and set it to start automatically at boot: systemctl start rpcbind.service systemctl enable rpcbind.service

systemctl start nfs systemctl enable nfs

Configuring NFS

nfs configuration file /etc/exports

Run the command man exports to find:

The format of the configuration file is:

Hosts (permissions) to access the shared directory

①Directory to be shared: Directory for accessing data

②Host to access: Single host: 172.16.1.7 or host name segment: 172.16.1.0/24 or 172.16.1.*

③Permissions: rw readable ro read-only sync write to remote disk (slow, safe) async asynchronously write to remote buffer (fast, unsafe)

root_squash anonuid=anonymous user's UID anongid=anonymous user's GID

all_squash No matter what user the client is, it will be treated as nfsnobody on the server

[root@nfs01 ~]# vim /etc/exports

Note: A directory can be shared with multiple hosts at the same time, as shown in the test figure above. Note that there is no space between the parentheses and the preceding character.

Create a directory: [root@nfs01 ~]# mkdir -p /data

The default user of nfs is nfsnobody, so you need to authorize the directory: [root@nfs01 ~]# chown -R nfsnobody.nfsnobody /data

Restart NFS: [root@nfs01 ~]# systemctl reload nfs or exportfs -r (smooth restart)

examine:

Open the web01 virtual machine and install the rpc and nfs services (in principle, the client only needs to install rpc, but we are testing the showmount command here)

Mount the shared directory and create a file test

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