Details on NFS

I need to know waht is NFS and how it is implemented?
Could you please give Detailed explanation?
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NFS is a way of mounting remote file resources on local machines- as if it was part of the local file struture. With Solaris it is implemented as so-

The NFS SERVER is the machine that makes file systems available to
the network. It does so by either EXPORTING (SunOS term) or SHARING
(Solaris term) them.

The NFS CLIENT is the machine that accesses file systems that have
been made available. It does so by MOUNTING them.

A number of different daemons are involved with NFS:

RPC.MOUNTD only runs on NFS servers. It answers initial requests from

NFS partitions can be mounted in one of two ways, hard or soft.

HARD MOUNTS are permanent mounts designed to look just like any
normal, local file system. If a partition that is hard mounted becomes
unavailable, client programs will keep trying to access it forever.
This will cause local processes to lock when a hard mounted disk goes
away. Hard mounts are the default type of mount.

SOFT MOUNTS will fail after a few retries if a remote partition
becomes unavailable. This is a problem if you are writing to the
partition, because you can never be sure that a write will actually
get processed  on the other hand, your local processes will not lock
up if that partition does go away. In general, soft mounts should only
be used if you are solely reading from a disk and even then it should
be understood that the mount is an unreliable one. If you soft mount a
partition that will be written to, you are nearly guaranteeing that
you will have problems.

There are a number of files related to NFS:
/etc/exports (SunOS) or /etc/dfs/dfstab (Solaris) lists which files to
export on a Server. These file are maintained by hand.

/etc/xtab (SunOS) or /etc/dfs/sharetab (Solaris) lists the filesystems
that actually are currently exported. They are maintained by exportfs
and share, respectively.

/etc/rmtab on a server lists filesystems that are remotely mounted by
clients. This file is maintained by rpc.mountd.

/etc/fstab (SunOS) or /etc/vfstab (Solaris) lists which files to mount
on a client. These files are maintained by hand.

/etc/mtab (SunOS) or /etc/mnttab (Solaris) on a client lists
filesystems which are currently mounted onto that client. The mount
and umount commands modify this file.

clients for file systems.

NFSD runs on NFS servers. They are the daemons that deal
with the majority of the client NFS requests.

On SunOS 4.1.X, BIODS (block I/O daemons) help clients with
their NFS requests.  These do not exist on Solaris 2.X.

LOCKD and STATD are a set of daemons that keep track of locks on NFS
files. There will typically be a set of daemons running on a client
and server.

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nateshavAuthor Commented:
Excelent answer

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