nfs是一种网络通讯共享协议，目前有几种版本，架构采用c/s模式；server端把文件系统共享出来，然后客户机就可以通过mount或者autofs及/etc/fstab等多种方式，如使用本地文件系统一起加载使用它。
其应用范围非常广泛.
     为了方便以后的进一步对nfs的理解及掌握，同时提供了英文文档。



   使用nfs必需的服务：
nfs — (/sbin/service nfs start) starts the NFS server and the appropriate RPC
processes to service requests for shared NFS file systems.
       启动nfs server和必要的支持共享nfs文件系统服务请求的进程
• nfslock — (/sbin/service nfslock start) is a mandatory service that starts the
appropriate RPC processes to allow NFS clients to lock files on the server.
       这一个必须要启用的服务，用于服务于nfs client锁定nfs server上面文件的合适的rpc进程
• portmap — accepts port reservations from local RPC services. These ports are then made
available (or advertised) so the corresponding remote RPC services access them. portmap
responds to requests for RPC services and sets up connections to the requested RPC
service. This is not used with NFSv4.
       保留本地rpc服务的端口，这些端口一直可用，以便对应的远程rpc服务访问它们。portmap服务响应来自rpc服务的请求，配置这些rpc服务请求的连接.在nfsv4版本中不在使用它



   The following RPC processes facilitate NFS services:
   通过下列的rpc进程来实现nfs的服务
• rpc.mountd — This process receives mount requests from NFS clients and verifies the
requested file system is currently exported. This process is started automatically by the nfs
service and does not require user configuration. This is not used with NFSv4.
                接受nfs client的加载请求，并验证所请求的文件系统是否目前被导出（nfs file system只有在nfs server被导出，才可以使用）。nfs service会自动启动它，因此不需要用户进行任何配置，在nfsv4不在使用它


• rpc.nfsd — Allows explicit NFS versions and protocols the server advertises to be defined. It
works with the Linux kernel to meet the dynamic demands of NFS clients, such as providing
server threads each time an NFS client connects. This process corresponds to the nfs
service.
                允许显式定义nfs server的协议及版本.它与kernel一同满足nfs client的动态需求，比如：为每个nfs client连接提供一个服务器的线程号。这个进程与nfs service有对应关系           


• rpc.lockd — allows NFS clients to lock files on the server. If rpc.lockd is not started, file
locking will fail. rpc.lockd implements the Network Lock Manager (NLM) protocol. This
process corresponds to the nfslock service. This is not used with NFSv4.
                允许nfs client锁定nfs server上面的文件。如果这个进程没启动，文件锁定会失败。它基于网格锁定管理器协议。这个进程对应于nfslock 服务，在nfs v4不在使用


• rpc.statd — This process implements the Network Status Monitor (NSM) RPC protocol
which notifies NFS clients when an NFS server is restarted without being gracefully brought
down. This process is started automatically by the nfslock service and does not require user
configuration. This is not used with NFSv4.
                当nfs server意外重启，通过网络状态监控rpc协议，通知nfs client.这个进程会通过nfslock服务自动启动，不用用户进行配置，在nfs v4中不在使用




• rpc.rquotad — This process provides user quota information for remote users. This process
is started automatically by the nfs service and does not require user configuration.
                为远程用户配置配额信息,会随着nfs 服务自动启动，不用自户配置




• rpc.idmapd — This process provides NFSv4 client and server upcalls which map between
on-the-wire NFSv4 names (which are strings in the form. of user@domain) and local UIDs and
GIDs. For idmapd to function with NFSv4, the /etc/idmapd.conf must be configured. This
service is required for use with NFSv4.
                 可以为nfsv4 client和nfs server的upcalls,配置on-the-ware nfsv4名字（采用user@domain的格式）和本地uids及gids的映射关系.要在nfsv4使用此功能，必须要配置/etc/idmapd.conf。从nfsv4中不在使用它