Introduction to NFS service and how to use it

1. Introduction to NFS service

NFS is the abbreviation of Network File System, that is, network file system. A protocol for distributed file systems, developed by Sun and announced in 1984. Function: Allow different machines and different operating systems to share individual data with each other through the network, allowing applications to access data located on the server disk through the network on the client side. It is a method to achieve disk file sharing between Unix-like systems. .

The basic principle of NFS is to "allow different clients and servers to share the same file system through a set of RPCs". It is independent of the operating system and allows different hardware and operating systems. systems to share files together.

NFS relies on the RPC protocol during file transfer or information transfer. RPC, remote procedure call, is a mechanism that enables the client to execute other system programs. NFS itself does not provide information transmission protocols and functions, but NFS allows us to share data through the network. This is because NFS uses some other transmission protocols. These transport protocols use this RPC function. It can be said that NFS itself is a program using RPC. In other words, NFS is an RPC SERVER. So wherever NFS is required the RPC service must be started. Summary: NFS is just a file system, and rpc is responsible for the transmission of information.

2. InstallationNFSService

NFSRequires two software packages

nfs-utils-* Includes basic NFScommands and monitoring programs

rpcbind-* Supports securityNFS RPCService connection

1.Check whether the system is installedNFS

rpm -qa|grep nfs

rpm -qa|grep rpcbind

If not, firstyum grouplist thenyum groupinstall "NFS"

3. NFSServer configuration

NFSCommon directories

/etc/exports NFSMain configuration file of the service

/usr/sbin/exportfs NFSService management command

/usr/sbin/showmount Client view command

/ var/lib/nfs/etab RecordNFSThe complete permission setting value of the shared directory

/var/lib/nfs/ xtab Record the client information that has logged in

NFSThe configuration file of the service is /etc/exports, The system does not have a default value, so this file may not exist. You can use vim to create it manually, and then write the configuration content in the file.

/etc/exportsFile content format:

<Output directory> [Client1 options (access rights, user mapping, other)] [Client2 options (access rights, user mapping , others)】

a.Output directory: The output directory refers to the directory in the NFS system that needs to be shared for client use

b.Client: A computer in the network that can access this NFS output directory

Commonly used client specification methods:

Specify the host with the ip address: 192.168.0.200

Specify all hosts in the subnet: 192.168.0.0/24 192.168.0.0/255.255.255.0

Specify the host of the domain name: david.bsmart.cn

All hosts in the specified domain name: *.bsmart.cn

All hosts: *

c.Options: Used to set the access permissions of the output directory, user mapping, etc.

NFS mainly has 3 type options:

Access permission options

Set the output directory read-only: ro

Set the output directory read-write: rw

User Mapping option

all_squash:Map all ordinary users and their groups for remote access to anonymous users or user groups (nfsnobody)

no_all_squash: Opposite of all_squash (default setting)

root_squash: Change The rootuser and its group are mapped to anonymous usersoruser group

no_root_squash: opposite to the above

anongid=xxx:Map all remote access users as anonymous users, and specify the user as a local user

anongid=xxx: Map all user groups for remote access to anonymous user group accounts, and specify the anonymous user group account as a local user group account

Other options (ignore, use the default value)

4. NFS Starting and stopping the server

After correctly configuring the /etc/exports file, you can start NFS Server.

1.Start the NFS server

In order for the nfs server to work properly, you need to Start the two services rpcbind and nfs, and rpcbind must be preceded by nfsStart

service rpcbind start

service nfs start

2.Query nfsserver status

service rpcbind status

service nfs status

3.stopnfsserver

To stop nfs, first stop nfs and then stop rpcbind Service, when there are other services in the system (such as nis) that need to be used, there is no need to stop the rpcbind service

service nfs stop

service rpcbind stop

4.Set the automatic startup status of nfs

chkconfig --add

chkconfig --level 35

5. Example

1.Change the of NFS server /home/cairui Shared to 192.168.66.128, permission read and write

#vim /etc/exports

/home/cairui 192.168.66.128/24(rw)

2.Restartrpcbindandnfsservice

service rpcbind restart

service nfs restart

exportfs

3.Use showmountcommand query on the server sideNFSShared status

showmount -e

showmount -a Display directory information that has been connected to the client

4.The client uses the showmount command to query## Sharing status of #nfs

Serverip

Customer Side mountnfsShared directory in the server

Command format: mount NFSServerIP: Shared directory local mount point directory

Check whether the mount is successful: mount|grep nfs

Modify the permissions on the server/home/cairui so that the client can write and read

Uninstall the mounted NFSshared directory

Format: umount /tmp/cai

Start automatic mountingnfsFile system

Format: :