33.4 NFS Daemons

   

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NFS uses a number of daemon processes to provide reliable file system access over a network. A number of clients may be accessing shared files, and it is the responsibility of the NFS system to guarantee file system integrity. NFS is a stateless server, which means that it does not keep a record of the state of files and clients that are accessing them. To keep consistency of files, a file locking mechanism is used through NFS daemons to ensure that files are properly locked when accessed by a client. Table 33-3 shows a list of NFS daemons and their functions on the client and server.

Table 33-3. NFS Daemons

Name	NFS System	Description
portmap	Both client and server	RPC daemon used in HP-UX 10.20 and earlier versions.
rpcbind	Both client and server	RPC daemon used in HP-UX 10.30 and later versions.
rpc.statd	Both client and server	RPC daemon used with the rpc.lockd daemon to provide crash recovery functions.
rpc.lockd	Both client and server	Used for file locking on both NFS servers and clients. Both client and server rpc.lockd daemons interact with each other to provide file locking functions.
nfsd	Server	The NFS server daemon. A number of server daemon processes (by default, 4) are started at startup time. All of these processes register themselves with portmap or rpcbind . A heavily loaded NFS server may start more daemon processes.
rpc.pcnfsd	Server	Used with PCNFS. Not required if all clients are UNIX machines.
rpc. mountd	Server	Keeps a record of mounted and exported file systems. Replies to mount requests .
biod	Client	Used to handle buffer cache in asynchronous I/O on NFS clients.

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