This file contains a list of entries. Each entry indicates a directory that is shared and how it is shared. A typical entry in /etc/exports consists of:

/shared/directory host(option_list)

For example:

/export 192.168.1.2(rw,fsid=0,sync,crossmnt)
/export/data 192.168.1.2(rw,bind=/data,sync)

Here the IP address 192.168.1.2 is used to identify the allowed client. You can also use the name of the host, a wild card indicating a set of hosts (*.abc.com, *, etc.), or netgroups (@my-hosts).

The directory which specifies fsid=0 is special in that it is the root of the filesystem that is exported, sometime referred to as the pseudo root filesystem. This directory must also have the crossmnt for correct operation with NFSv4. All other directories exported via NFSv4 must be mounted below this point. If you want to export a directory that is not normally below this exported root, it needs to be bound into the exported tree. This can be done using the bind= syntax.

In the example above, /data is not below the /export, but we want to export it anyway, so we export /export/data, and specify that the /data directory should be bound to that name. The directory /export/data must exist and should normally be empty.

When clients mount from this server, that should just mount servername:/ rather than servername:/export. It is not necessary to also mount servername:/data and that will automatically appear beneath wherever servername:/ was mounted.

This file contains a few parameters that determine NFSv4 server daemon behavior. Importantly, the parameter NFSv4_SUPPORT must be set to yes. This parameter determines whether the NFS server supports NFSv4 exports and clients.

Every user on a Linux machine has a name and ID. idmapd does the name-to-ID mapping for NFSv4 requests to the server and replies to the client. This must be running on both server and client for NFSv4, because NFSv4 uses only names for its communication.

Make sure that there is a uniform way in which usernames and IDs (uid) are assigned to users across machines that might probably be sharing file systems using NFS. This can be achieved by using NIS, LDAP, or any uniform domain authentication mechanism in your domain.

For proper function, the parameter Domain must be set the same for both, client and server in this file. If you are not sure, leave the domain as localdomain in the server and client files. A sample configuration file looks like the following:

[General] 

Verbosity = 0 
Pipefs-Directory = /var/lib/nfs/rpc_pipefs
Domain = localdomain

[Mapping]

Nobody-User = nobody
Nobody-Group = nobody

Do not change these parameters unless you know exactly what you are doing. For further reference, read the man page of idmapd and idmapd.conf; man idmapd, man idmapd.conf.

After changing /etc/exports or /etc/sysconfig/nfs, start or restart the nfs server service with rcnfsserver restart. After changing /etc/idmapd.conf, reload the configuration file with the command killall -HUP rpc.idmapd.

If this service needs to start at boot time, run the command chkconfig nfsserver on.