Difference between revisions of "NFS"

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{{Article summary text|Article covers configuration of NFSv4 which is an open standard network file sharing protocol.}}
 
{{Article summary text|Article covers configuration of NFSv4 which is an open standard network file sharing protocol.}}
 
{{Article summary heading|Related}}
 
{{Article summary heading|Related}}
{{Article summary wiki|NFSv3}} - Depreciated v3 format.
+
{{Article summary wiki|NFS_Troubleshooting}} - Dedicated article for common problems and solutions.
 +
{{Article summary wiki|NFSv3}} - Deprecated v3 format.
 
{{Article summary end}}
 
{{Article summary end}}
  
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==== File system ====
 
==== 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.
+
{{Note|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 {{ic|/etc/exports}} which are relative to the NFS root.  In this example, the NFS root will be {{ic|/srv/nfs4}} and we will be sharing {{ic|/mnt/music}}.
 
Define any NFS shares in {{ic|/etc/exports}} which are relative to the NFS root.  In this example, the NFS root will be {{ic|/srv/nfs4}} and we will be sharing {{ic|/mnt/music}}.
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==== Exports ====
 
==== Exports ====
 
Add directories to be shared and an ip address or hostname(s) of client machines that will be allowed to mount them in {{ic|/etc/exports}}:
 
Add directories to be shared and an ip address or hostname(s) of client machines that will be allowed to mount them in {{ic|/etc/exports}}:
  /srv/nfs4/ 192.168.0.0/24(rw,fsid=0,no_subtree_check)
+
  /srv/nfs4/ 192.168.0.1/24(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
+
  /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.
 
Users need-not open the share to the entire subnet; one can specify a single IP address or hostname as well.
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===Client===
 
===Client===
The client configuration only involves the {{ic|/etc/idmapd.conf}} file.
+
No special setup is required on the client-side.
  
==== ID mapping====
+
==Mounting from Linux==
Edit {{ic|/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:
 
Show the server's exported filesystems:
  showmount -e servername
+
  $ showmount -e servername
  
 
Then just mount as normal:  
 
Then just mount as normal:  
 
  # mount -t nfs4 servername:/music /mountpoint/on/client
 
  # mount -t nfs4 servername:/music /mountpoint/on/client
  
Some additional mount options to consider are included:
+
===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 {{ic|/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
  
*rsize=8192
+
{{Note|Additional mount options can be specified here. Consult the NFS man page for further information.}}
*wsize=8192
+
Some additional mount options to consider are include:
 +
 
 +
*rsize=8192 and wsize=8192
 
*timeo=14
 
*timeo=14
 
*intr
 
*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 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 higher values such as 8192 can improve throughput.  This is not universal.  It is recommended to test after making this change.
  
 
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 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.  
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The intr option allows signals to interrupt the file operation if a major timeout occurs for a hard-mounted share.
 
The intr option allows signals to interrupt the file operation if a major timeout occurs for a hard-mounted share.
  
====Auto mounting====
+
===Using autofs===
Consult the [[Systemd#Remote_filesystem_mounts|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 {{ic|/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.
 
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 ==
 
== Mounting from Windows ==
{{note|only the Enterprise and Ultimate versions of Windows 7 include "Client for NFS"}}
+
{{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.[https://social.technet.microsoft.com/Forums/en-CA/w7itpronetworking/thread/40cc01e3-65e4-4bb6-855e-cef1364a60ac]}}
 +
{{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).
 
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").
 
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").
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{{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 {{ic|showmount -e servername}} from the terminal}}
 
{{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 {{ic|showmount -e servername}} from the terminal}}
 
==Troubleshooting==
 
===exportfs: /etc/exports:2: syntax error: bad option list===
 
Delete all space from the option list in {{ic|/etc/exports}}
 
 
===mount.nfs4: No such device===
 
Check that you have loaded the {{ic|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 {{ic|/etc/conf.d/nfs-common.conf}}
 
{{bc|<nowiki>
 
# /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"
 
</nowiki>}}
 
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 {{ic|--manage-gids}} start-up flag for {{ic|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.
 

Revision as of 13:58, 22 November 2012

Template:Article summary start Template:Article summary text Template:Article summary heading Template:Article summary wiki - Dedicated article for common problems and solutions. Template:Article summary wiki - Deprecated v3 format. Template:Article summary end

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

Note: 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

No special setup is required on the client-side.

Mounting from Linux

Show the server's exported filesystems:

$ showmount -e servername

Then just mount as normal:

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

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.

Some additional mount options to consider are include:

  • rsize=8192 and 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 higher values such as 8192 can improve throughput. This is not universal. It is recommended to test after making this change.

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.

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