一、NFS简介
NFS是网络文件系统（Network File System）的简称，是分布式计算机系统的一个组成部分，可实现在异构网络上共享和装配远程文件系统。
1、设置Linux系统之间的文件共享（Linux与Windows中间文件共享采用SAMBA服务）；
2、NFS只是一种文件系统，本身没有传输功能，是基于RPC协议实现的，才能达到两个Linux系统之间的文件目录共享；
3、NFS为C/S架构；
二、NFS应用
1、我的服务器磁盘满了，而我又不能停机添加硬盘或者更换容量更大的服务器，硬盘热插拔服务器除外。
2、配置SSH免密码登录，需要把两台机器的SSH加密串copy到authorzied_keys文件中，例如配置hadoop应用，hadoop允许新添加DataNode节点，如果没有NFS那么各个节点配置SSH免密码登录，两三个节点还好说，万一有一千个节点，今天坏掉一个节点，又新加一个，明天又扩容一个节点，配置SSH免密码真是牵一发而动全身，有了NFS各个节点可以把加密串配置到NFS共享目录中
三、安装软件
在192.168.1.104上共享一个目录给其他主机使用，因此1.104作为服务器端，需要检查服务器端软件安装情况，并完成软件安装。
1、检查软件是否安装
[root@bogon ~]# rpm -q nfs-utils portmap
nfs-utils-1.2.3-36.el6.i686
package portmap is not installed
2、下载安装portmap
[root@bogon ~]# wget ftp://ftp.pbone.net/mirror/archive.download.redhat.com/pub/redhat/linux/6.1/en/os/i386/RedHat/RPMS/portmap-4.0-17.i386.rpm
Connecting to ftp.pbone.net|85.14.85.4|:21... connected.
Logging in as anonymous ... Logged in!
==> SYST ... done. ==> PWD ... done.
==> TYPE I ... done. ==> CWD (1) /mirror/archive.download.redhat.com/pub/redhat/linux/6.1/en/os/i386/RedHat/RPMS ... done.
==> SIZE portmap-4.0-17.i386.rpm ... 30245
==> PASV ... done. ==> RETR portmap-4.0-17.i386.rpm ... done.
Length: 30245 (30K) (unauthoritative)
100%[======================================>] 30,245 59.1K/s in 0.5s
[root@bogon ~]# ls
anaconda-ks.cfg install.log install.log.syslog portmap-4.0-17.i386.rpm
[root@bogon ~]# rpm -ivh portmap-4.0-17.i386.rpm
Preparing... ########################################### [100%]
1:portmap ########################################### [100%]
[root@bogon ~]# service portmap start
Starting portmapper: portmap: relocation error: portmap: symbol errno, version GLIBC_2.0 not defined in file libc.so.6 with link time reference
[FAILED]
[root@bogon ~]# yum install libc.so.6
Loaded plugins: fastestmirror, security
Loading mirror speeds from cached hostfile
* base: mirrors.163.com
* extras: mirrors.163.com
* updates: mirrors.163.com
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package glibc.i686 0:2.12-1.107.el6 will be updated
--> Processing Dependency: glibc = 2.12-1.107.el6 for package: glibc-common-2.12-1.107.el6.i686
---> Package glibc.i686 0:2.12-1.166.el6_7.7 will be an update
--> Running transaction check
---> Package glibc-common.i686 0:2.12-1.107.el6 will be updated
---> Package glibc-common.i686 0:2.12-1.166.el6_7.7 will be an update
--> Finished Dependency Resolution
Complete!
[root@bogon ~]# service portmap start
Starting portmapper: portmap: relocation error: portmap: symbol errno, version GLIBC_2.0 not defined in file libc.so.6 with link time reference
[FAILED]
[root@bogon ~]# yum install libc.so.6 libnsl.so.1
Package glibc-2.12-1.166.el6_7.7.i686 already installed and latest version
Package glibc-2.12-1.166.el6_7.7.i686 already installed and latest version
Package glibc-2.12-1.166.el6_7.7.i686 already installed and latest version
Nothing to do
[root@bogon ~]# service portmap start
Starting portmapper: portmap: relocation error: portmap: symbol errno, version GLIBC_2.0 not defined in file libc.so.6 with link time reference
[FAILED]
[root@bogon ~]# yum install glibc
Loaded plugins: fastestmirror, security
Complete!
[root@bogon ~]#
[root@bogon ~]# service portmap start
Starting portmapper: portmap: relocation error: portmap: symbol errno, version GLIBC_2.0 not defined in file libc.so.6 with link time reference
[FAILED]
[root@bogon ~]# reboot
Broadcast message from root@bogon
(/dev/pts/0) at 4:04 ...
The system is going down for reboot NOW!
[root@bogon ~]# Last login: Fri Feb 26 03:46:42 2016 from 192.168.1.103
[root@bogon ~]# wget ftp://carroll.aset.psu.edu/pub/.mirrors/1/rh-mirror.redhat.com/redhat/linux/5.0/en/os/i386/RedHat/RPMS/portmap-4.0-7.i386.rpm
==> SYST ... done. ==> PWD ... done.
==> TYPE I ... done. ==> CWD (1) /mirror/archive.download.redhat.com/pub/redhat/linux/5.0/en/os/i386/RedHat/RPMS ... done.
==> SIZE portmap-4.0-7.i386.rpm ... 23064
==> PASV ... done. ==> RETR portmap-4.0-7.i386.rpm ... done.
Length: 23064 (23K) (unauthoritative)
100%[=====================================>] 23,064 54.6K/s in 0.4s
2016-02-26 04:07:42 (54.6 KB/s) - portmap-4.0-7.i386.rpm saved [23064]
[root@bogon ~]# clear
[root@bogon ~]# ls
anaconda-ks.cfg install.log install.log.syslog portmap-4.0-17.i386.rpm portmap-4.0-7.i386.rpm
[root@bogon ~]# rpm -q portmap
portmap-4.0-17.i386
[root@bogon ~]# rpm -e portmap-4.0-17.i386
[root@bogon ~]# rpm -ivh portmap-4.0-7.i386.rpm
Preparing... ########################################### [100%]
1:portmap ########################################### [100%]
[root@bogon ~]# service portmap start
Starting portmapper: [ OK ]
[root@bogon ~]#
[root@bogon ~]# rpm -q nfs-utils portmap
nfs-utils-1.2.3-64.el6.i686
portmap-4.0-7.i386
[root@bogon ~]# service nfs status
rpc.svcgssd is stopped
rpc.mountd is stopped
nfsd is stopped
rpc.rquotad is stopped
[root@bogon ~]# service nfs start
Starting NFS services: [ OK ]
Starting NFS quotas: [ OK ]
Starting NFS mountd: [ OK ]
Starting NFS daemon: [ OK ]
[root@bogon ~]# [ OK ]
四、服务器端配置
把1.104的/opt/share_nfs共享给1.105机器，配置如下：
root@bogon ~]# mkdir /opt/share_nfs
[root@bogon ~]# vi /etc/exports
/opt/share_nfs 192.168.1.105(rw)
[root@bogon ~]# service portmap restart
Stopping portmap services: [FAILED]
Starting portmapper: [ OK ]
[root@bogon ~]# service nfs restart
Shutting down NFS daemon: [ OK ]
Shutting down NFS mountd: [ OK ]
Shutting down NFS quotas: [ OK ]
Starting NFS services: [ OK ]
Starting NFS quotas: [ OK ]
Starting NFS mountd: [ OK ]
Starting NFS daemon: [ OK ]
[root@bogon ~]# exportfs [ OK ]
/opt/share_nfs 192.168.1.105
[root@bogon ~]#
[root@bogon ~]# service portmap restart
Stopping portmap services: [FAILED]
Starting portmapper: [ OK ]
[root@bogon ~]# service nfs restart
Shutting down NFS daemon: [ OK ]
Shutting down NFS mountd: [ OK ]
Shutting down NFS quotas: [ OK ]
Starting NFS services: [ OK ]
Starting NFS quotas: [ OK ]
Starting NFS mountd: [ OK ]
Starting NFS daemon: [ OK ]
[root@bogon ~]# exportfs [ OK ]
/opt/share_nfs 192.168.1.105
五、客户端配置以及验证
[root@bogon ~]# showmount -e 192.168.1.104
Export list for 192.168.1.104:
/opt/share_nfs 192.168.1.105
[root@bogon ~]# cd /m
media/ misc/ mnt/
[root@bogon ~]# mount 192.168.1.104:/opt/share_nfs /mnt/
[root@bogon ~]# echo "gaojingsong write nfslog in 1.105" >/mnt/test.log
-bash: /mnt/test.log: Permission denied（解决方案，修改服务器目录权限）
[root@bogon ~]# echo "gaojingsong write nfslog in 1.105" >/mnt/test.log
[root@bogon ~]# cat /mnt/test.log
gaojingsong write nfslog in 1.105
[root@bogon ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:10:37:75
inet addr:192.168.1.105 Bcast:192.168.1.255 Mask:255.255.255.0
错误解决方案：
1、客服端Permission denied（解决方案，修改1.104服务器目录权限）
[root@bogon ~]# chmod 777 -R /opt/share_nfs
[root@bogon ~]# cd /opt/share_nfs
[root@bogon share_nfs]# ls -l
total 4
-rw-r--r--. 1 nfsnobody nfsnobody 34 Feb 26 04:21 test.log
[root@bogon share_nfs]# cat test.log
gaojingsong write nfslog in 1.105
[root@bogon share_nfs]# hostname -i
hostname: Unknown host
[root@bogon share_nfs]# ifconfig
eth1 Link encap:Ethernet HWaddr 00:0C:29:2B:F8:93
inet addr:192.168.1.104 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fe2b:f893/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:956 errors:0 dropped:0 overruns:0 frame:0
TX packets:745 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:127238 (124.2 KiB) TX bytes:91020 (88.8 KiB)
Interrupt:19 Base address:0x2000
2、服务器端安装portmap 软件后重启报错
[root@bogon ~]# service portmap start
Starting portmapper: portmap: relocation error: portmap: symbol errno, version GLIBC_2.0 not defined in file libc.so.6 with link time reference[FAILED]
解决方案：检查portmap 是否对应支持相应的操作系统