Difference between revisions of "NFS"

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(Starting the client: removed initscripts reference)
(streamlining article / work in progress)
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==Installing==
 
==Installing==
Both client and server only require {{Pkg|nfs-utils}} from the [[official repositories]].
+
Both client and server only require the {{Pkg|nfs-utils}} package.
  
==Configuring==
+
{{Note|It is HIGHLY recommended to use a time sync daemon on ALL nodes of your network to keep client/server clocks in syncWithout accurate clocks on all nodes, NFS can introduce unwanted delays!}}
===Time synchronization===
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In order for NFS to function properly, both server and client must have closely matching time values.  If the clocks on the clients differ from the server too much, then basic functions like file copy operations may hang for a very long time leaving the system unusable until they resumeThe clocks do not have to match to micro/nano second accuracies, but ideally they should be within 1 second of each other. 
+
  
The [[NTP]] system is recommended to sync both the server and the clients to the highly accurate NTP servers available on the Internet. For a small system like a home network, the ntpdate utility may be used to sync both servers and clients to the same time.  For a larger installation, it may be desirable to install an OpenNTP server (see [[NTP]]) onto the same machine acting as the NFS server, and then all clients on the network would sync time values from the server.  This has the advantage of lowering the stress on the external NTP servers, and in assuring that the NFS clients will use the exact time that the NFS server has, even if the NFS server experiences some drift.
+
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===
 
===Server===
The server configuration involves the {{ic|/etc/idmapd.conf}} file and the {{ic|/etc/exports}} file to export shares. Further tweaking can be done by editing {{ic|/etc/conf.d/nfs-server.conf}}.
+
==== ID Mapping ====
 +
Edit {{ic|/etc/idmapd.conf}} and define a Domain.
  
====Server ID mapping====
+
Example:
The {{ic|/etc/idmapd.conf}} file needs to be edited. You'll need to at the very least specify your Domain there. Example:
+
 
  [General]
 
  [General]
 
   
 
   
 
  Verbosity = 1
 
  Verbosity = 1
 
  Pipefs-Directory = /var/lib/nfs/rpc_pipefs
 
  Pipefs-Directory = /var/lib/nfs/rpc_pipefs
  '''Domain = archlinux.org'''
+
  '''Domain = atomic'''
 
   
 
   
 
  [Mapping]
 
  [Mapping]
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  Nobody-Group = nobody
 
  Nobody-Group = nobody
  
====Exports====
+
==== Filesystem ====
All the NFS shares are defined in {{ic|/etc/exports}}. Add directories which you want to share and ip addresses or hostnames of client machines that will be allowed to mount them:
+
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.
  /mnt/music 192.168.0.12(rw,no_subtree_check)
+
  
You can also share it to a whole subnet:
+
Define any NFS shares in {{ic|/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.
  /mnt/music 192.168.0.0/24(rw,no_subtree_check)
+
{{Note|The old NFSv3-style 192.168.0.*-scheme is ''no longer'' supported.}}
+
  
A typical NFSv4 export would look like this:
+
  # mkdir -p /srv/nfs4/music
  /mnt      192.168.0.12(rw,fsid=0,no_subtree_check)
+
/mnt/music 192.168.0.12(rw,no_subtree_check)
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{{Note|The {{ic|1=fsid=0}} is required for the root filesystem being exported. {{ic|/mnt}} is the NFS root here (due to the {{ic|1=fsid=0}} entry). Everything else that you want to be shared over NFS must be accessible under {{ic|/mnt}}. Setting an NFS root is required. For exporting directories outside the NFS root, see below.}}
+
  
For more information about all available options see {{ic|man 5 exports}}.
+
Now mount the actual target share, /mnt/music to the NFS share via the a mount command:
  
=====Exporting directories outside your NFS root=====
+
  # mount --bind /mnt/music /srv/nfs4/music
To do this, you will need to use bind mounts. For example, to bind {{ic|/home/john}} to {{ic|/mnt/john}}:
+
  # mount --bind /home/john /mnt/john
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To make it stick across server reboots add the bind mount to {{ic|/etc/fstab}}:
+
/home/john    /mnt/john    none    bind  0 0
+
  
Then, {{ic|/mnt/john}} needs to be added to {{ic|/etc/exports}}:
+
To make it stick across server reboots, add the bind mount to {{ic|/etc/fstab}}:
/mnt      192.168.0.12(rw,fsid=0,no_subtree_check)
+
  /mnt/music /srv/nfs4/music none  bind  0  0
  /mnt/music 192.168.0.12(rw,no_subtree_check)
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/mnt/john 192.168.0.12(rw,no_subtree_check,'''nohide''')
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The {{ic|nohide}} option is '''required''', because the kernel NFS server automatically hides mounted directories.
+
  
====Starting the server====
+
==== Exports ====
 +
Add directories to be shared and an ip address or hostname(s) of client machines that will be allowed to mount them:
 +
/srv/nfs4/ 192.168.0.0/24(rw,fsid=0,no_subtree_check)
 +
/srv/nfs4/music 192.168.0.0/24(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 {{ic|1=fsid=0}} is required for the root filesystem being exported. {{ic|/mnt}} is the NFS root here (due to the {{ic|1=fsid=0}} entry). Everything else that you want to be shared over NFS must be accessible under {{ic|/mnt}}. Setting an NFS root is required. For exporting directories outside the NFS root, see below.}}
 +
For more information about all available options see {{ic|man 5 exports}}.
 +
 
 +
====Starting the Server====
  
 
To start the NFS server, use:
 
To start the NFS server, use:
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===Client===
 
===Client===
The client configuration only involves the {{ic|/etc/idmapd.conf}} file. If your client also acts as a server for other machines on the network, then you will still have to configure the files covered in the server section.
+
The client configuration only involves the {{ic|/etc/idmapd.conf}} file.
 +
 
 +
==== ID Mapping====
 +
Edit {{ic|/etc/idmapd.conf}} and define the same Domain specified in the server's config:
  
====Client ID mapping====
+
Example:
The {{ic|/etc/idmapd.conf}} file needs to be edited on all clients. '''The Domain entry should be identical to the one on the server''' (see the ''Server ID mapping'' section). Example:
+
 
  [General]
 
  [General]
 
   
 
   
 
  Verbosity = 1
 
  Verbosity = 1
 
  Pipefs-Directory = /var/lib/nfs/rpc_pipefs
 
  Pipefs-Directory = /var/lib/nfs/rpc_pipefs
  '''Domain = archlinux.org'''
+
  '''Domain = atomic'''
 
   
 
   
 
  [Mapping]
 
  [Mapping]
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  # systemctl start nfsd.service rpc-idmapd.service
 
  # systemctl start nfsd.service rpc-idmapd.service
  
==Mounting NFS shares on the client==
+
====Mounting NFS shares on the client====
 
Show the server's exported filesystems:
 
Show the server's exported filesystems:
  showmount -e server
+
  showmount -e servername
 +
 
 
Then just mount as normal:  
 
Then just mount as normal:  
# rc.d start rpcbind nfs-common
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  # mount -t nfs4 servername:/music /mountpoint/on/client
  # mount -t nfs4 server:/ /mnt/server/
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# mount -t nfs4 server:/music /mnt/music/
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# mount -t nfs4 server:/john /mnt/john
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Replacing 'server' with the hostname or IP address of your NFS server and of course 'server', 'music' and 'john' with the names of whatever directories you exported on the server.
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{{note|The root of the path on the server is the NFS root specified; all paths must be specified relative to it.}}
+
  
 
===Auto mounting===
 
===Auto mounting===

Revision as of 20:53, 16 October 2012

Note: this article covers NFSv4, for the older version 3 see NFSv3

Network File System (NFS), is an open standard network file sharing protocol.

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

Filesystem

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 a 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:

/srv/nfs4/ 192.168.0.0/24(rw,fsid=0,no_subtree_check)
/srv/nfs4/music 192.168.0.0/24(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 filesystem being exported. /mnt 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 /mnt. 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 the /etc/idmapd.conf file.

ID Mapping

Edit /etc/idmapd.conf and define the same Domain 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

Starting the client

To start the NFS client:

# systemctl start nfsd.service rpc-idmapd.service

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


Auto mounting

  • With Initscripts: If you want to auto mount the NFS shares on boot, you will have to make sure that the network(or any other networking daemon that you use), rpcbind, nfs-common daemons are started up and also in that order. Do NOT background the daemons since the order in which they start up is important. Additionally you will also want to start netfs daemon which handles the clean unmount of NFS shares while shutting down the client machine. The netfs daemon can be backgrounded without any issues.
DAEMONS=(... network rpcbind nfs-common @netfs ...)

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

Using fstab

Using fstab is useful when you have a server which is always on, and the NFS shares are available whenever your client boots up. Edit your /etc/fstab file, and add an appropriate line in there reflecting your setup.

server:/ /mnt/nfsshare nfs4 defaults 0 0
Note: where server is the server hostname or IP address

If you wish to specify a packet size for read and write packets, specify them in your /etc/fstab entry. Read the NFS man page for further information, including all available mount options.

Using autofs

Using autofs is useful when you have multiple machines that you want to connect via NFS and they could both be clients as well as servers. The reason this method is preferable over the earlier one is that if one of the machine(server) is switched off, the client will not throw errors about being unable to find NFS shares. Please see the relevant section on the autofs#NFS_Network_mounts page for setting up NFS shares.

Mounting from Windows

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 it's 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://server/

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

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

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.