NFS 是Network File System的缩写，即网络文件系统，一种使用于分散式文件系统的协定
NFS通过网络让不同的机器、不同的操作系统能够彼此分享个别的数据，例如将/home设置为共享目录，然后共享给网络中的其它服务器，这样每台机器就不必单独建立自己的/home路径了，NFS独立于操作系统，容许不同硬件及操作系统的系统共同进行文件的分享，是在类Unix系统间实现磁盘文件共享的一种方法
NFS本身没有提供信息传输的协议和功能，而是使用RPC服务完成这部分功能。可以说NFS本身就是使用RPC服务的一个程序，或者说NFS也是一个RPC SERVER。所以只要用到NFS的地方都要启动RPC服务，不论是NFS server还是NFS client，可以这么理解RPC和NFS之间的关系：NFS是一个文件系统，而RPC负责信息的传输
一，系统环境
Linux Distribution：Ubuntu 14
二，安装Linux NFS
[plain] view plain copy sean@sean:~$ sudo apt-get install nfs-kernel-server [sudo] password for sean: Reading package lists... Done Building dependency tree Reading state information... Done The following extra packages will be installed: keyutils libgssglue1 libnfsidmap2 libtirpc1 nfs-common rpcbind Suggested packages: open-iscsi watchdog The following NEW packages will be installed: keyutils libgssglue1 libnfsidmap2 libtirpc1 nfs-common nfs-kernel-server rpcbind 0 upgraded, 7 newly installed, 0 to remove and 159 not upgraded. Need to get 460 kB of archives. After this operation, 2,049 kB of additional disk space will be used. Do you want to continue? [Y/n] Y Get:1 http://cn.archive.ubuntu.com/ubuntu/ trusty/main libgssglue1 amd64 0.4-2ubuntu1 [19.7 kB] Get:2 http://cn.archive.ubuntu.com/ubuntu/ trusty/main libnfsidmap2 amd64 0.25-5 [32.2 kB] Get:3 http://cn.archive.ubuntu.com/ubuntu/ trusty/main libtirpc1 amd64 0.2.2-5ubuntu2 [71.3 kB] Get:4 http://cn.archive.ubuntu.com/ubuntu/ trusty/main keyutils amd64 1.5.6-1 [33.6 kB] Get:5 http://cn.archive.ubuntu.com/ubuntu/ trusty-updates/main rpcbind amd64 0.2.1-2ubuntu2.2 [37.1 kB] Get:6 http://cn.archive.ubuntu.com/ubuntu/ trusty-updates/main nfs-common amd64 1:1.2.8-6ubuntu1.2 [181 kB] Get:7 http://cn.archive.ubuntu.com/ubuntu/ trusty-updates/main nfs-kernel-server amd64 1:1.2.8-6ubuntu1.2 [85.8 kB] Fetched 460 kB in 16s (27.2 kB/s) Selecting previously unselected package libgssglue1:amd64. (Reading database ... 168701 files and directories currently installed.) Preparing to unpack .../libgssglue1_0.4-2ubuntu1_amd64.deb ... Unpacking libgssglue1:amd64 (0.4-2ubuntu1) ... Selecting previously unselected package libnfsidmap2:amd64. Preparing to unpack .../libnfsidmap2_0.25-5_amd64.deb ... Unpacking libnfsidmap2:amd64 (0.25-5) ... Selecting previously unselected package libtirpc1:amd64. Preparing to unpack .../libtirpc1_0.2.2-5ubuntu2_amd64.deb ... Unpacking libtirpc1:amd64 (0.2.2-5ubuntu2) ... Selecting previously unselected package keyutils. Preparing to unpack .../keyutils_1.5.6-1_amd64.deb ... Unpacking keyutils (1.5.6-1) ... Selecting previously unselected package rpcbind. Preparing to unpack .../rpcbind_0.2.1-2ubuntu2.2_amd64.deb ... Unpacking rpcbind (0.2.1-2ubuntu2.2) ... Selecting previously unselected package nfs-common. Preparing to unpack .../nfs-common_1:1.2.8-6ubuntu1.2_amd64.deb ... Unpacking nfs-common (1:1.2.8-6ubuntu1.2) ... Selecting previously unselected package nfs-kernel-server. Preparing to unpack .../nfs-kernel-server_1:1.2.8-6ubuntu1.2_amd64.deb ... Unpacking nfs-kernel-server (1:1.2.8-6ubuntu1.2) ... Processing triggers for man-db (2.6.7.1-1ubuntu1) ... Processing triggers for ureadahead (0.100.0-16) ... ureadahead will be reprofiled on next reboot Setting up libgssglue1:amd64 (0.4-2ubuntu1) ... Setting up libnfsidmap2:amd64 (0.25-5) ... Setting up libtirpc1:amd64 (0.2.2-5ubuntu2) ... Setting up keyutils (1.5.6-1) ... Setting up rpcbind (0.2.1-2ubuntu2.2) ... Removing any system startup links for /etc/init.d/rpcbind ... rpcbind start/running, process 12074 Processing triggers for ureadahead (0.100.0-16) ... Setting up nfs-common (1:1.2.8-6ubuntu1.2) ... Creating config file /etc/idmapd.conf with new version Creating config file /etc/default/nfs-common with new version Adding system user `statd' (UID 118) ... Adding new user `statd' (UID 118) with group `nogroup' ... Not creating home directory `/var/lib/nfs'. statd start/running, process 12307 gssd stop/pre-start, process 12341 idmapd start/running, process 12399 Processing triggers for ureadahead (0.100.0-16) ... Setting up nfs-kernel-server (1:1.2.8-6ubuntu1.2) ... Creating config file /etc/exports with new version Creating config file /etc/default/nfs-kernel-server with new version * Not starting NFS kernel daemon: no exports. Processing triggers for libc-bin (2.19-0ubuntu6.7) ... Processing triggers for ureadahead (0.100.0-16) ...通过安装日志可以发现总共会安装keyutils，libgssglue1，libnfsidmap2，libtirpc1，nfs-common，nfs-kernel-server，rpcbind这7个包
很多文档中安装的包为portmap，但是这个包已经被rpcbind替代
[plain] view plain copy sean@sean:~$ sudo apt-get install portmap Reading package lists... Done Building dependency tree Reading state information... Done Note, selecting 'rpcbind' instead of 'portmap' rpcbind is already the newest version. 0 upgraded, 0 newly installed, 0 to remove and 164 not upgraded.rpcbind包安装完成后会自动启动rpcbind服务
[plain] view plain copy sean@sean:~$ ps -ef|grep rpcbind root 807 1 0 22:27 ? 00:00:00 rpcbind sean 10215 9528 0 22:48 pts/6 00:00:00 grep --color=auto rpcbind但是由于目前NFS的配置文件为空，NFS服务并没有启动
三，配置NFS服务
从安装日志中我们可以发现NFS服务的配置文件为/etc/exports，并且这个文件在安装过程中已经生成好了，我们所要做的就是将NFS配置信息添加到这个文件中
[plain] view plain copy sean@sean:~$ sudo vi /etc/exports [plain] view plain copy # /etc/exports: the access control list for filesystems which may be exported # to NFS clients. See exports(5). # # Example for NFSv2 and NFSv3: # /srv/homes hostname1(rw,sync,no_subtree_check) hostname2(ro,sync,no_subtree_check) # # Example for NFSv4: # /srv/nfs4 gss/krb5i(rw,sync,fsid=0,crossmnt,no_subtree_check) # /srv/nfs4/homes gss/krb5i(rw,sync,no_subtree_check) /home/sean/shareDir 192.168.137.129(rw,no_root_squash,async)其中中的最后一行为新添加的NFS配置，NFS配置信息格式如下：
[plain] view plain copy <共享目录> [客户端1 选项（访问权限,用户映射,其他）] [客户端2 选项（访问权限,用户映射,其他）]1，共享目录：
共享目录是指NFS系统中需要共享给客户机使用的目录
2，客户端：
客户端是指网络中可以访问NFS共享目录的计算机
客户端常用的指定方式：
(1)指定ip地址的主机：192.168.0.1 (2)指定子网中的所有主机：192.168.0.0/255.255.255.0 (3)指定域名的主机：www.sean.com (4)指定域中的所有主机：*.sean.com (5)所有主机：*
3，选项：
选项用来设置输出目录的访问权限、用户映射等，NFS主要有3类选项：
访问权限选项：
(1)设置输出目录只读：ro (2)设置输出目录读写：rw
用户映射选项：
(1)all_squash：将远程访问的所有普通用户及所属组都映射为匿名用户或用户组（nfsnobody） (2)no_all_squash：与all_squash取反（默认设置） (3)root_squash：将root用户及所属组都映射为匿名用户或用户组（默认设置） (4)no_root_squash：与rootsquash取反 (5)anonuid=xxx：将远程访问的所有用户都映射为匿名用户，并指定该用户为本地用户（UID=xxx） (6)anongid=xxx：将远程访问的所有用户组都映射为匿名用户组账户，并指定该匿名用户组账户为本地用户组账户（GID=xxx）
其它选项：
(1)secure：限制客户端只能从小于1024的tcp/ip端口连接nfs服务器（默认设置） (2)insecure：允许客户端从大于1024的tcp/ip端口连接服务器 (3)sync：将数据同步写入内存缓冲区与磁盘中，效率低，但可以保证数据的一致性 (4)async：将数据先保存在内存缓冲区中，必要时才写入磁盘 (5)wdelay：检查是否有相关的写操作，如果有则将这些写操作一起执行，这样可以提高效率（默认设置） (6)no_wdelay：若有写操作则立即执行，应与sync配合使用 (7)subtree：若输出目录是一个子目录，则nfs服务器将检查其父目录的权限(默认设置) (8)no_subtree：即使输出目录是一个子目录，nfs服务器也不检查其父目录的权限，这样可以提高效率
四，启动NFS服务
[plain] view plain copy sean@sean:~$ sudo service nfs-kernel-server start * Exporting directories for NFS kernel daemon... exportfs: /etc/exports [1]: Neither 'subtree_check' or 'no_subtree_check' specified for export "192.168.137.129:/home/sean/shareDir". Assuming default behaviour ('no_subtree_check'). NOTE: this default has changed since nfs-utils version 1.0.x [ OK ] * Starting NFS kernel daemon sean@sean:~$ sudo service nfs-kernel-server status nfsd running sean@sean:~$ ps -ef|grep nfsd root 10536 2 0 23:40 ? 00:00:00 [nfsd4] root 10537 2 0 23:40 ? 00:00:00 [nfsd4_callbacks] root 10539 2 0 23:40 ? 00:00:00 [nfsd] root 10540 2 0 23:40 ? 00:00:00 [nfsd] root 10541 2 0 23:40 ? 00:00:00 [nfsd] root 10542 2 0 23:40 ? 00:00:00 [nfsd] root 10543 2 0 23:40 ? 00:00:00 [nfsd] root 10544 2 0 23:40 ? 00:00:00 [nfsd] root 10545 2 0 23:40 ? 00:00:00 [nfsd] root 10546 2 0 23:40 ? 00:00:00 [nfsd] sean 10566 9528 0 23:41 pts/6 00:00:00 grep --color=auto nfsd通过命令可以看到文件夹已经被共享
[plain] view plain copy sean@sean:~$ showmount -e Export list for sean: /home/sean/shareDir 192.168.137.129
五，客户端挂载NFS共享目录
[plain] view plain copy sean@ubuntu:~$ sudo mount 192.168.137.128:/home/sean/shareDir /home/sean/shared mount: wrong fs type, bad option, bad superblock on 192.168.137.128:/home/sean/shareDir, missing codepage or helper program, or other error (for several filesystems (e.g. nfs, cifs) you might need a /sbin/mount.<type> helper program) In some cases useful info is found in syslog - try dmesg | tail or so上网查看了一下错误原因，是因为客户端没有安装nfs-common包
[plain] view plain copy sean@ubuntu:~$ sudo apt-get install nfs-common之后再次使用挂载命令即可，此时如果我们再次查看客户端挂载的磁盘，就可以看到NFS共享目录已经被挂载上了
[plain] view plain copy sean@ubuntu:~$ df Filesystem 1K-blocks Used Available Use% Mounted on udev 488800 4 488796 1% /dev tmpfs 99904 1456 98448 2% /run /dev/sda1 19478204 3745568 14720156 21% / none 4 0 4 0% /sys/fs/cgroup none 5120 0 5120 0% /run/lock none 499512 152 499360 1% /run/shm none 102400 40 102360 1% /run/user /dev/sr0 1044480 1044480 0 100% /media/sean/Ubuntu 14.04.4 LTS amd64 192.168.137.128:/home/sean/shareDir 19478272 4288896 14176896 24% /home/sean/shared此时如果我们在128的/home/sean/shareDir目录下创建一个文件，在129的/home/sean/shared目录下可以看到一个名称相同的文件，并且文件的内容也相同
六，开机启动NFS服务
安装完成之后查看系统服务
[plain] view plain copy sean@sean:~$ runlevel N 2 sean@sean:~$ ll /etc/rc2.d total 20 drwxr-xr-x 2 root root 4096 6月 20 23:25 ./ drwxr-xr-x 132 root root 12288 6月 26 20:16 ../ -rw-r--r-- 1 root root 677 2月 17 12:59 README lrwxrwxrwx 1 root root 20 2月 22 06:33 S20kerneloops -> ../init.d/kerneloops* lrwxrwxrwx 1 root root 27 6月 20 23:25 S20nfs-kernel-server -> ../init.d/nfs-kernel-server* lrwxrwxrwx 1 root root 15 2月 22 06:33 S20rsync -> ../init.d/rsync* lrwxrwxrwx 1 root root 27 2月 22 06:33 S20speech-dispatcher -> ../init.d/speech-dispatcher* lrwxrwxrwx 1 root root 15 2月 22 06:33 S50saned -> ../init.d/saned* lrwxrwxrwx 1 root root 19 2月 22 06:33 S70dns-clean -> ../init.d/dns-clean* lrwxrwxrwx 1 root root 18 2月 22 06:33 S70pppd-dns -> ../init.d/pppd-dns* lrwxrwxrwx 1 root root 21 2月 22 06:33 S99grub-common -> ../init.d/grub-common* lrwxrwxrwx 1 root root 18 2月 22 06:33 S99ondemand -> ../init.d/ondemand* lrwxrwxrwx 1 root root 18 2月 22 06:33 S99rc.local -> ../init.d/rc.local*nfs-kernel-server是自动启动，就不需要再进行修改了，而rpcbind就比较麻烦了，找了半天才找到vi /etc/init/rpcbind-boot.conf
[plain] view plain copy # portmap-boot description "Upstart job to start rpcbind on boot only" author "Clint Byrum" emits start-rpcbind start on virtual-filesystems and net-device-up IFACE=lo task exec initctl emit --no-wait start-rpcbind ON_BOOT=y可以见到这个服务设为开机启动了
七，开机自动挂载共享盘
这时候我们需要修改的文件是/etc/fstab，命令格式如下：
[plain] view plain copy <NFS服务端>:<共享目录> <本地目录> <文件系统类型> <选项> <dump> <pass>每个字段的具体含义这里就不详细解释了，vi /etc/fstab，在文件中添加下面这行配置
[plain] view plain copy 192.168.137.128:/home/sean/shareDir /home/sean/shared nfs defaults 0 0系统每次启动时即会自动挂载共享盘
