NFS

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Installing

Both client and server only require the nfs-utils package.

Note: It is HIGHLY recommended to use a time sync daemon on ALL nodes of your network to keep client/server clocks in sync. Without accurate clocks on all nodes, NFS can introduce unwanted delays!

The NTP system is recommended to sync both the server and the clients to the highly accurate NTP servers available on the Internet.

Configuring

Server

ID mapping

Edit /etc/idmapd.conf and define a Domain.

Example:

[General]

Verbosity = 1
Pipefs-Directory = /var/lib/nfs/rpc_pipefs
Domain = atomic

[Mapping]

Nobody-User = nobody
Nobody-Group = nobody

File system

For security reasons, it is recommended to use an NFS export root which will keep users limited to that mount point only. The following example illustrates this concept.

Define any NFS shares in /etc/exports which are relative to the NFS root. In this example, the NFS root will be /srv/nfs4 and we will be sharing /mnt/music.

# mkdir -p /srv/nfs4/music

Now mount the actual target share, /mnt/music to the NFS share via the mount command:

# mount --bind /mnt/music /srv/nfs4/music

To make it stick across server reboots, add the bind mount to /etc/fstab:

/mnt/music /srv/nfs4/music  none   bind   0   0

Exports

Add directories to be shared and an ip address or hostname(s) of client machines that will be allowed to mount them in /etc/exports:

/srv/nfs4/ 192.168.0.1/24(rw,fsid=0,no_subtree_check)
/srv/nfs4/music 192.168.0.1/24(rw,no_subtree_check,nohide) # note the nohide option which is applied to mounted directories on the filesystem

Users need-not open the share to the entire subnet; one can specify a single IP address or hostname as well.

Note: The fsid=0 is required for the root file system being exported. /srv/nfs4 is the NFS root here (due to the fsid=0 entry). Everything else that you want to be shared over NFS must be accessible under /srv/nfs4. Setting an NFS root is required. For exporting directories outside the NFS root, see below.

For more information about all available options see man 5 exports.

Starting the server

To start the NFS server, use:

# systemctl start nfsd.service rpc-idmapd.service rpc-mountd.service rpcbind.service

Client

The client configuration only involves editing /etc/idmapd.conf so that the Domain matches the one specified in the server's config:

Example:

[General]

Verbosity = 1
Pipefs-Directory = /var/lib/nfs/rpc_pipefs
Domain = atomic

[Mapping]

Nobody-User = nobody
Nobody-Group = nobody

[Translation]
Method = nsswitch

Mounting NFS shares on the client

Show the server's exported filesystems:

showmount -e servername

Then just mount as normal:

# mount -t nfs4 servername:/music /mountpoint/on/client

Some additional mount options to consider are included:

• rsize=8192
• wsize=8192
• timeo=14
• intr

The rsize value is the number of bytes used when reading from the server. The wsize value is the number of bytes used when writing to the server. The default for both is 1024, but using 8192 greatly improves throughput and is recommended.

The timeo value is the amount of time, in tenths of a second, to wait before resending a transmission after an RPC timeout. After the first timeout, the timeout value is doubled for each retry for a maximum of 60 seconds or until a major timeout occurs. If connecting to a slow server or over a busy network, better performance can be achieved by increasing this timeout value.

The intr option allows signals to interrupt the file operation if a major timeout occurs for a hard-mounted share.

Auto mounting

Consult the Systemd/RemoteFilesystem page and make sure to enable rpc-idmapd.service for user id mapping.

After adding the daemons, auto mounting of NFS shares can be handled in one of two ways:

Using fstab

Using fstab is useful for a server which is always on, and the NFS shares are available whenever the client boots up. Edit /etc/fstab file, and add an appropriate line reflecting the setup setup. Example:

servername:/music   /mountpoint/on/client   nfs4   rsize=8192,wsize=8192,timeo=14,intr	0 0

Note: Additional mount options can be specified here. Consult the NFS man page for further information.

Using autofs

Using autofs is useful when multiple machines want to connect via NFS; they could both be clients as well as servers. The reason this method is preferable over the earlier one is that if the server is switched off, the client will not throw errors about being unable to find NFS shares. See autofs#NFS Network mounts for details.

Mounting from Windows

Warning: Serious performance issues may occur (it randomly takes 30-60 seconds to display a folder, 2 MB/s file copy speed on gigabit LAN, ...) to which Microsoft does not have a solution yet.[1]

Note: Only the Enterprise and Ultimate versions of Windows 7 include "Client for NFS"

NFS shares can be mounted from windows if the "Client for NFS" service is actived (which it is not by default). To install the service go to "Programs and features" either through the control panel or by typing it in the search box from the start menu and click on "Turn Windows features on or off". Locate the "Services for NFS" and activate it as well as both subservices ("Administrative tools" and "Client for NFS").

Some global options can be set by opening the "Services for Network File System" (locate it with the search box) and right clicking on the client->properties.

Warning: Under Windows the share is addressed by its full path on the server, not just the path relative to the nfsroot! If in doubt run showmount -e servername from cmd.exe

Mounting from OS X

Note: OS X by default uses a insecure (>1024) port to mount a share.

Either export the share with the insecure flag, and mount using Finder:

Go > Connect to Server > nfs://servername/

Or, mount the share using a secure port using the terminal:

# sudo mount -t nfs -o resvport servername:/ /Volumes/servername/

Warning: Under OS X the share is addressed by its full path on the server, not just the path relative to the nfsroot! If in doubt run showmount -e servername from the terminal

Troubleshooting

exportfs: /etc/exports:2: syntax error: bad option list

Delete all space from the option list in /etc/exports

mount.nfs4: No such device

Check that you have loaded the nfs module

lsmod | grep nfs

and if previous returns empty or only nfsd-stuff, do

modprobe nfs

mount.nfs4: access denied by server while mounting

Check that the permissions on your client's folder are correct. Try using 755.

Permissions issues

If you find that you cannot set the permissions on files properly, make sure the user/group you are chowning are on both the client and server. If that does not help, try modifying these lines in /etc/conf.d/nfs-common.conf

# /etc/conf.d/nfs-common.conf

# Do you want to start the statd daemon? It is not needed for NFSv4.
NEED_STATD="no"

# Do you want to start the idmapd daemon? It is only needed for NFSv4.
NEED_IDMAPD="yes"

Restart the nfs-common daemon for the changes to take effect. I restarted all the other daemons as well, just to be sure.

Group/gid permissions issues

If NFS shares mount fine, and are fully accessible to the owner, but not to group members; check the number of groups that user belongs to. NFS has a limit of 16 on the number of groups a user can belong to. If you have users with more then this, you need to enable the --manage-gids start-up flag for rpc.mountd on the NFS server.

/etc/conf.d/nfs-server.conf

# Options for rpc.mountd.
# If you have a port-based firewall, you might want to set up
# a fixed port here using the --port option.
# See rpc.mountd(8) for more details.

MOUNTD_OPTS="--manage-gids"

Lock problems

If you got error such as this:

mount.nfs: rpc.statd is not running but is required for remote locking.
mount.nfs: Either use '-o nolock' to keep locks local, or start statd.
mount.nfs: an incorrect mount option was specified

To fix this, you need to change the "NEED_STATD" value in:

/etc/conf.d/nfs-common.conf
 
NEED_STATD="no"

Remember to start all the services - nfsd.service rpc-idmapd.service rpc-mountd.service rpcbind.service, not just the nfsd.