Difference between revisions of "NFS"

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[[Category:File systems]]
 
[[Category:Networking]]
 
[[Category:Networking]]
 
[[ar:NFS]]
 
[[ar:NFS]]
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[[it:NFSv4]]
 
[[it:NFSv4]]
 
[[zh-CN:NFS]]
 
[[zh-CN:NFS]]
{{Article summary start}}
+
{{Related articles start}}
{{Article summary text|Article covers configuration of NFSv4 which is an open standard network file sharing protocol.}}
+
{{Related|NFS Troubleshooting}}
{{Article summary heading|Related}}
+
{{Related articles end}}
{{Article summary wiki|NFS Troubleshooting}} - Dedicated article for common problems and solutions.
+
{{Article summary wiki|NFSv3}} - Deprecated v3 format.
+
{{Article summary end}}
+
 
From [[Wikipedia: Network File System|Wikipedia]]:  
 
From [[Wikipedia: Network File System|Wikipedia]]:  
:''Network File System (NFS) is a distributed file system protocol originally developed by Sun Microsystems in 1984, allowing a user on a client computer to access files over a network in a manner similar to how local storage is accessed.''
+
: ''Network File System (NFS) is a distributed file system protocol originally developed by Sun Microsystems in 1984, allowing a user on a client computer to access files over a network in a manner similar to how local storage is accessed.''
  
==Installing==
+
== Installation ==
Both client and server only require the [[Pacman|installation]] of the {{Pkg|nfs-utils}} package.
+
 
 +
Both client and server only require the [[pacman|installation]] of the {{Pkg|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.}}
 
{{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.}}
Line 23: Line 22:
  
 
===Server===
 
===Server===
 +
 
==== ID mapping ====
 
==== ID mapping ====
 +
 
Edit {{ic|/etc/idmapd.conf}} and set the {{ic|Domain}} field to your domain name.
 
Edit {{ic|/etc/idmapd.conf}} and set the {{ic|Domain}} field to your domain name.
  
Line 38: Line 39:
 
Nobody-Group = nobody
 
Nobody-Group = nobody
 
</nowiki>}}
 
</nowiki>}}
 +
 
==== File system ====
 
==== 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.}}
 
{{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}}.
  
{{bc|# mkdir -p /srv/nfs4/music}}
+
# mkdir -p /srv/nfs4/music
  
 
Read/Write permissions must be set on the music directory so clients may write to it.  
 
Read/Write permissions must be set on the music directory so clients may write to it.  
Line 49: Line 52:
 
Now mount the actual target share, {{ic|/mnt/music}} to the NFS share via the mount command:
 
Now mount the actual target share, {{ic|/mnt/music}} to the NFS share via the mount command:
  
{{bc|# mount --bind /mnt/music /srv/nfs4/music}}
+
# mount --bind /mnt/music /srv/nfs4/music
  
 
To make it stick across server reboots, add the bind mount to {{ic|fstab}}:
 
To make it stick across server reboots, add the bind mount to {{ic|fstab}}:
Line 57: Line 60:
  
 
==== 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|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|exports}}:
 
{{hc|/etc/exports|<nowiki>
 
{{hc|/etc/exports|<nowiki>
Line 68: Line 72:
  
 
If you modify {{ic|/etc/exports}} while the server is running, you must re-export them for changes to take effect:
 
If you modify {{ic|/etc/exports}} while the server is running, you must re-export them for changes to take effect:
{{bc|# exportfs -ra}}
+
# exportfs -rav
  
====Starting the server====
+
==== Starting the server ====
  
[[Daemons|Start/enable]] {{ic|rpc-idmapd.service}} and {{ic|rpc-mountd.service}}. Note that these units require other services, which are launched automatically by [[systemd]].
+
Start {{ic|rpc-idmapd.service}} and {{ic|rpc-mountd.service}} [[systemd#Using units|using systemd]]. If you want them running at boot time, enable them. Note that these units require other services, which are launched automatically by [[systemd]].
  
===Client===
+
==== Firewall configuration ====
Clients need {{Pkg|nfs-utils}} to connect, but no special setup is required when connecting to NFS 4 servers.
+
  
====Mounting from Linux====
+
To enable access through a firewall, tcp and udp ports 111, 2049, and 20048 need to be opened. To configure this for [[iptables]], edit {{ic|/etc/iptables/iptables.rules}} to include the following lines:
Show the server's exported filesystems:
+
 
{{bc|$ showmount -e servername}}
+
{{hc|/etc/iptables/iptables.rules|<nowiki>
 +
-A INPUT -p tcp -m tcp --dport 111 -j ACCEPT
 +
-A INPUT -p tcp -m tcp --dport 2049 -j ACCEPT
 +
-A INPUT -p tcp -m tcp --dport 20048 -j ACCEPT
 +
-A INPUT -p udp -m udp --dport 111 -j ACCEPT
 +
-A INPUT -p udp -m udp --dport 2049 -j ACCEPT
 +
-A INPUT -p udp -m udp --dport 20048 -j ACCEPT
 +
</nowiki>}}
 +
 
 +
To apply changes, restart {{ic|iptables}} service.
 +
 
 +
=== Client ===
 +
 
 +
Clients with a kernel version prior to 3.12.7-2 need to start {{ic|rpc-gssd.service}} to avoid an approx 15 seconds delay with an accompanying error in dmsg that reads, "RPC: AUTH_GSS upcall timed out" due to a kernel bug.
 +
 
 +
{{Note|The server does not need to run this service.}}
 +
{{Warning|Starting this service without having it configured properly will result in error messages like:
 +
rpc.gssd[30473]: ERROR: Key table file '/etc/krb5.keytab' not found while beginning keytab scan for keytab 'FILE:/etc/krb5.keytab'
 +
rpc.gssd[30473]: ERROR: gssd_refresh_krb5_machine_credential: no usable keytab entry found in keytab /etc/krb5.keytab for connection with host server.domain
 +
rpc.gssd[30473]: ERROR: No credentials found for connection to server server.domain
 +
and might lock up any NFS mount on the system when mounting and unmounting some mounts very often.
 +
}}
 +
An alternative is to blacklist the module {{ic|rpcsec_gss_krb5}} and rebooting afterwards:
 +
# echo "blacklist rpcsec_gss_krb5" > /etc/modprobe.d/rpcsec_gss_krb5-blacklist.conf
 +
# reboot
 +
as described [https://bugzilla.redhat.com/show_bug.cgi?id=1001934 on Red Hat's Bugzilla].
 +
 
 +
==== Mounting from Linux ====
 +
 
 +
Show the server's exported file systems:
 +
$ showmount -e servername
  
 
Then mount omitting the server's NFS export root:  
 
Then mount omitting the server's NFS export root:  
{{bc|# mount -t nfs4 servername:/music /mountpoint/on/client}}
+
# mount -t nfs4 servername:/music /mountpoint/on/client
 +
 
 +
{{Note|Server name needs to be a valid hostname (not just IP address). Otherwise mounting of remote share will hang.}}
 +
 
 +
===== using /etc/fstab =====
  
=====/etc/fstab Settings=====
 
 
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. Again, the server's NFS export root is omitted.
 
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. Again, the server's NFS export root is omitted.
 +
 
{{hc|/etc/fstab|<nowiki>
 
{{hc|/etc/fstab|<nowiki>
 
servername:/music  /mountpoint/on/client  nfs4  rsize=8192,wsize=8192,timeo=14,intr,_netdev 0 0
 
servername:/music  /mountpoint/on/client  nfs4  rsize=8192,wsize=8192,timeo=14,intr,_netdev 0 0
 
</nowiki>}}
 
</nowiki>}}
  
{{Note|Additional mount options can be specified here. Consult the NFS man page for further information.}}
+
{{Note|Consult the ''NFS'' and ''mount'' man pages for more mount options.}}
 +
 
 
Some additional mount options to consider are include:
 
Some additional mount options to consider are include:
  
* {{ic|1=rsize=8192}} and {{ic|1=wsize=8192}}
+
; rsize and wsize: The {{ic|rsize}} value is the number of bytes used when reading from the server. The {{ic|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, see [[#Performance tuning]].
* {{ic|1=timeo=14}}
+
* {{ic|1=intr}}
+
* {{ic|1=_netdev}}
+
  
The {{ic|rsize}} value is the number of bytes used when reading from the server. The {{ic|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.
+
; timeo: The {{ic|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 {{ic|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.  
+
; intr: The {{ic|intr}} option allows signals to interrupt the file operation if a major timeout occurs for a hard-mounted share.
  
The {{ic|intr}} option allows signals to interrupt the file operation if a major timeout occurs for a hard-mounted share.
+
; _netdev: The {{ic|_netdev}} option tells the system to wait until the network is up before trying to mount the share. systemd assumes this for NFS, but anyway it is good practice to use it for all types of networked file systems
  
The {{ic|_netdev}} option tells the system to wait until the network is up before trying to mount the share. systemd assumes this for NFS, but anyway it is good practice to use it for all types of networked filesystems
+
{{Note|Setting the sixth field (fs_passno) to a nonzero value may lead to unexpected behaviour, e.g. hangs when the systemd automount waits for a check which will never happen.}}
  
=====Using autofs=====
+
===== 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 Ultimate and Enterprise editions of Windows 7 and the Enterprise edition of Windows 8 include "Client for NFS".}}
+
 
 +
{{Note|Only the Ultimate and Enterprise editions of Windows 7 and the Enterprise edition of Windows 8 include "Client for NFS".}}
 
NFS shares can be mounted from Windows if the "Client for NFS" service is activated (which it is not by default).
 
NFS shares can be mounted from Windows if the "Client for NFS" service is activated (which it is not by default).
 
To install the service go to "Programs and features" in the Control Panel and click on "Turn Windows features on or off". Locate "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" in the Control Panel and click on "Turn Windows features on or off". Locate "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 click on client->properties.  
+
Some global options can be set by opening the "Services for Network File System" (locate it with the search box) and right click on ''client > properties''.
  
 
{{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]}}
 
{{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]}}
Line 123: Line 160:
  
 
==== Mounting from OS X ====
 
==== Mounting from OS X ====
{{note|OS X by default uses an insecure (>1024) port to mount a share.}}
+
 
 +
{{Note|OS X by default uses an insecure (>1024) port to mount a share.}}
 
Either export the share with the {{ic|insecure}} flag, and mount using Finder:
 
Either export the share with the {{ic|insecure}} flag, and mount using Finder:
  
Line 129: Line 167:
  
 
Or, mount the share using a secure port using the terminal:
 
Or, mount the share using a secure port using the terminal:
{{bc|# sudo mount -t nfs -o resvport servername:/srv/nfs4 /Volumes/servername}}
+
# mount -t nfs -o resvport servername:/srv/nfs4 /Volumes/servername
 +
 
 +
== Tips and tricks ==
 +
 
 +
=== Performance tuning ===
 +
 
 +
In order to get the most out of NFS, it is necessary to tune the {{ic|rsize}} and {{ic|wsize}} mount options to meet the requirements of the network configuration.
 +
 
 +
=== Automatic mount handling ===
 +
 
 +
This trick is useful for laptops that require nfs shares from a local wireless network. If the nfs host becomes unreachable, the nfs share will be unmounted to hopefully prevent system hangs when using the hard mount option. See https://bbs.archlinux.org/viewtopic.php?pid=1260240#p1260240
 +
 
 +
Make sure that the NFS mount points are correctly indicated in {{ic|/etc/fstab}}:
 +
 
 +
{{hc|$ cat /etc/fstab|<nowiki>
 +
lithium:/mnt/data          /mnt/data         nfs noauto,noatime,rsize=32768,wsize=32768,intr,hard 0 0
 +
lithium:/var/cache/pacman  /var/cache/pacman nfs noauto,noatime,rsize=32768,wsize=32768,intr,hard 0 0</nowiki>
 +
}}
 +
 
 +
The {{ic|noauto}} mount option tells systemd not to automatically mount the shares at boot. systemd would otherwise attempt to mount the nfs shares that may or may not exist on the network causing the boot process to appear to stall on a blank screen.
 +
 
 +
In order to mount NFS share by non-root user {{ic|user}} may be required to be added to fstab entry. Also enable rpc-statd.service.
 +
 
 +
Create the {{ic|auto_share}} script that will be used by ''cron'' to check if the NFS host is reachable,
 +
 
 +
{{hc|/root/bin/auto_share|<nowiki>
 +
#!/bin/bash
 +
 
 +
SERVER="YOUR_NFS_HOST"
 +
 
 +
MOUNT_POINTS=$(sed -e '/^.*#/d' -e '/^.*:/!d' -e 's/\t/ /g' /etc/fstab | tr -s " " | cut -f2 -d" ")
 +
 
 +
ping -c 1 "${SERVER}" &>/dev/null
 +
 
 +
if [ $? -ne 0 ]; then
 +
    # The server could not be reached, unmount the shares
 +
    for umntpnt in ${MOUNT_POINTS}; do
 +
        umount -l -f $umntpnt &>/dev/null
 +
    done
 +
else
 +
    # The server is up, make sure the shares are mounted
 +
    for mntpnt in ${MOUNT_POINTS}; do
 +
        mountpoint -q $mntpnt || mount $mntpnt
 +
    done
 +
fi
 +
</nowiki>}}
 +
 
 +
# chmod +x /root/bin/auto_share
 +
 
 +
Create the root cron entry to run {{ic|auto_share}} every minute:
 +
 
 +
{{hc|# crontab -e|<nowiki>
 +
* * * * * /root/bin/auto_share
 +
</nowiki>}}
 +
 
 +
A systemd unit file can also be used to mount the NFS shares at startup. The unit file is not necessary if NetworkManager is installed and configured on the client system. See [[#NetworkManager dispatcher]].
 +
 
 +
{{hc|/etc/systemd/system/auto_share.service|<nowiki>
 +
[Unit]
 +
Description=NFS automount
 +
 
 +
[Service]
 +
Type=oneshot
 +
RemainAfterExit=yes
 +
ExecStart=/root/bin/auto_share
 +
 
 +
[Install]
 +
WantedBy=multi-user.target
 +
</nowiki>}}
 +
 
 +
Now enable {{ic|auto_share}}.
 +
 
 +
==== NetworkManager dispatcher ====
 +
 
 +
In addition to the method described previously, NetworkManager can also be configured to run a script on network status change.
 +
 
 +
Enable and start the {{ic|NetworkManager-dispatcher}} service.
 +
 
 +
The easiest method for mount shares on network status change is to just symlink to the {{ic|auto_share}} script:
 +
 
 +
# ln -s /root/bin/auto_share /etc/NetworkManager/dispatcher.d/30_nfs.sh
 +
 
 +
Or use the following mounting script that checks for network availability:
 +
 
 +
{{hc|/etc/NetworkManager/dispatcher.d/30_nfs.sh|<nowiki>
 +
#!/bin/bash
 +
 
 +
SSID="CHANGE_ME"
 +
 
 +
MOUNT_POINTS=$(sed -e '/^.*#/d' -e '/^.*:/!d' -e 's/\t/ /g' /etc/fstab | tr -s " " | cut -f2 -d" ")
 +
 
 +
ISNETUP=$(nmcli dev wifi | \grep $SSID | tr -s ' ' | cut -f 10 -d ' ') 2>/dev/null
 +
 
 +
# echo "$ISNETUP" >> /tmp/nm_dispatch_log
 +
 
 +
if [[ "$ISNETUP" == "yes" ]]; then
 +
    for mntpnt in ${MOUNT_POINTS}; do
 +
        mountpoint -q $mntpnt || mount $mntpnt
 +
    done
 +
else
 +
    for srvexp in ${MOUNT_POINTS}; do
 +
        umount -l -f $srvexp &>/dev/null
 +
    done
 +
fi
 +
</nowiki>}}
 +
 
 +
Now when the wireless SSID "CHANGE_ME" goes up or down, the {{ic|nfs.sh}} script will be called to mount or unmount the shares as soon as possible.
 +
 
 +
=== Configure NFS fixed ports ===
 +
 
 +
{{Out of date|This section was originally refered to NFS version 3.}}
 +
If you have a port-based [[firewall]], you might want to set up a fixed ports. For rpc.statd and rpc.mountd you should set following settings in {{ic|/etc/conf.d/nfs-common}} and {{ic|/etc/conf.d/nfs-server}} (ports can be different):
 +
 
 +
{{hc|/etc/conf.d/nfs-common|2=STATD_OPTS="-p 4000 -o 4003"}}
 +
{{hc|/etc/conf.d/nfs-server|2=MOUNTD_OPTS="--no-nfs-version 2 -p 4002"}}
 +
{{hc|/etc/modprobe.d/lockd.conf|2=# Static ports for NFS lockd
 +
options lockd nlm_udpport=4001 nlm_tcpport=4001}}
 +
 
 +
After restart {{ic|nfs-common}} {{ic|nfs-server}} daemons and reload {{ic|lockd}} modules you can check used ports with following command:
 +
{{hc|$ rpcinfo -p|
 +
  program vers proto  port  service
 +
    100000    4  tcp    111  portmapper
 +
    100000    3  tcp    111  portmapper
 +
    100000    2  tcp    111  portmapper
 +
    100000    4  udp    111  portmapper
 +
    100000    3  udp    111  portmapper
 +
    100000    2  udp    111  portmapper
 +
    100024    1  udp  4000  status
 +
    100024    1  tcp  4000  status
 +
    100021    1  udp  4001  nlockmgr
 +
    100021    3  udp  4001  nlockmgr
 +
    100021    4  udp  4001  nlockmgr
 +
    100021    1  tcp  4001  nlockmgr
 +
    100021    3  tcp  4001  nlockmgr
 +
    100021    4  tcp  4001  nlockmgr
 +
    100003    2  tcp  2049  nfs
 +
    100003    3  tcp  2049  nfs
 +
    100003    4  tcp  2049  nfs
 +
    100003    2  udp  2049  nfs
 +
    100003    3  udp  2049  nfs
 +
    100003    4  udp  2049  nfs
 +
    100005    3  udp  4002  mountd
 +
    100005    3  tcp  4002  mountd
 +
}}
 +
 
 +
Then, you need to open the ports 111-2049-4000-4001-4002-4003 TCP and UDP.
  
 
== Troubleshooting ==
 
== Troubleshooting ==
''There is a dedicated article [[NFS Troubleshooting]].''
+
 
 +
There is a dedicated article [[NFS Troubleshooting]].
 +
 
 +
== See also ==
 +
 
 +
* See also [[Avahi]], a Zeroconf implementation which allows automatic discovery of NFS shares.
 +
* HOWTO: [[Diskless network boot NFS root]]
 +
* [http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?topic=/com.ibm.aix.prftungd/doc/prftungd/nfs_perf.htm NFS Performance Management]
 +
* If you are setting up the Arch Linux NFS server for use by Windows clients through Microsoft's SFU, you will save a lot of time and hair-scratching by looking at [https://bbs.archlinux.org/viewtopic.php?pid=523934#p523934 this forum post] first !
 +
* [http://blogs.msdn.com/sfu/archive/2008/04/14/all-well-almost-about-client-for-nfs-configuration-and-performance.aspx Microsoft Services for Unix NFS Client info]
 +
* [http://blogs.msdn.com/sfu/archive/2007/05/01/unix-interoperability-and-windows-vista.aspx Unix interoperability and Windows Vista] Prerequisites to connect to NFS with Vista

Revision as of 18:14, 16 January 2014

Related articles

From Wikipedia:

Network File System (NFS) is a distributed file system protocol originally developed by Sun Microsystems in 1984, allowing a user on a client computer to access files over a network in a manner similar to how local storage is accessed.

Installation

Both client and server only require the installation of 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.

Configuration

Server

ID mapping

Edit /etc/idmapd.conf and set the Domain field to your domain name.

/etc/idmapd.conf
[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

Read/Write permissions must be set on the music directory so clients may write to it.

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 fstab:

/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 exports:

/etc/exports
/srv/nfs4/ 192.168.0.1/24(rw,fsid=root,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 file system.

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

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

If you modify /etc/exports while the server is running, you must re-export them for changes to take effect:

# exportfs -rav

Starting the server

Start rpc-idmapd.service and rpc-mountd.service using systemd. If you want them running at boot time, enable them. Note that these units require other services, which are launched automatically by systemd.

Firewall configuration

To enable access through a firewall, tcp and udp ports 111, 2049, and 20048 need to be opened. To configure this for iptables, edit /etc/iptables/iptables.rules to include the following lines:

/etc/iptables/iptables.rules
-A INPUT -p tcp -m tcp --dport 111 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 2049 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 20048 -j ACCEPT
-A INPUT -p udp -m udp --dport 111 -j ACCEPT
-A INPUT -p udp -m udp --dport 2049 -j ACCEPT
-A INPUT -p udp -m udp --dport 20048 -j ACCEPT

To apply changes, restart iptables service.

Client

Clients with a kernel version prior to 3.12.7-2 need to start rpc-gssd.service to avoid an approx 15 seconds delay with an accompanying error in dmsg that reads, "RPC: AUTH_GSS upcall timed out" due to a kernel bug.

Note: The server does not need to run this service.
Warning: Starting this service without having it configured properly will result in error messages like:
rpc.gssd[30473]: ERROR: Key table file '/etc/krb5.keytab' not found while beginning keytab scan for keytab 'FILE:/etc/krb5.keytab'
rpc.gssd[30473]: ERROR: gssd_refresh_krb5_machine_credential: no usable keytab entry found in keytab /etc/krb5.keytab for connection with host server.domain
rpc.gssd[30473]: ERROR: No credentials found for connection to server server.domain

and might lock up any NFS mount on the system when mounting and unmounting some mounts very often.

An alternative is to blacklist the module rpcsec_gss_krb5 and rebooting afterwards:

# echo "blacklist rpcsec_gss_krb5" > /etc/modprobe.d/rpcsec_gss_krb5-blacklist.conf
# reboot

as described on Red Hat's Bugzilla.

Mounting from Linux

Show the server's exported file systems:

$ showmount -e servername

Then mount omitting the server's NFS export root:

# mount -t nfs4 servername:/music /mountpoint/on/client
Note: Server name needs to be a valid hostname (not just IP address). Otherwise mounting of remote share will hang.
using /etc/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. Again, the server's NFS export root is omitted.

/etc/fstab
servername:/music   /mountpoint/on/client   nfs4   rsize=8192,wsize=8192,timeo=14,intr,_netdev	0 0
Note: Consult the NFS and mount man pages for more mount options.

Some additional mount options to consider are include:

rsize and wsize
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, see #Performance tuning.
timeo
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.
intr
The intr option allows signals to interrupt the file operation if a major timeout occurs for a hard-mounted share.
_netdev
The _netdev option tells the system to wait until the network is up before trying to mount the share. systemd assumes this for NFS, but anyway it is good practice to use it for all types of networked file systems
Note: Setting the sixth field (fs_passno) to a nonzero value may lead to unexpected behaviour, e.g. hangs when the systemd automount waits for a check which will never happen.
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

Note: Only the Ultimate and Enterprise editions of Windows 7 and the Enterprise edition of Windows 8 include "Client for NFS".

NFS shares can be mounted from Windows if the "Client for NFS" service is activated (which it is not by default). To install the service go to "Programs and features" in the Control Panel and click on "Turn Windows features on or off". Locate "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 click on client > properties.

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]

To mount a share using Explorer:

Computer > Map network drive > servername:/srv/nfs4/music

Mounting from OS X

Note: OS X by default uses an 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:

# mount -t nfs -o resvport servername:/srv/nfs4 /Volumes/servername

Tips and tricks

Performance tuning

In order to get the most out of NFS, it is necessary to tune the rsize and wsize mount options to meet the requirements of the network configuration.

Automatic mount handling

This trick is useful for laptops that require nfs shares from a local wireless network. If the nfs host becomes unreachable, the nfs share will be unmounted to hopefully prevent system hangs when using the hard mount option. See https://bbs.archlinux.org/viewtopic.php?pid=1260240#p1260240

Make sure that the NFS mount points are correctly indicated in /etc/fstab:

$ cat /etc/fstab
lithium:/mnt/data           /mnt/data	        nfs noauto,noatime,rsize=32768,wsize=32768,intr,hard 0 0
lithium:/var/cache/pacman   /var/cache/pacman	nfs noauto,noatime,rsize=32768,wsize=32768,intr,hard 0 0

The noauto mount option tells systemd not to automatically mount the shares at boot. systemd would otherwise attempt to mount the nfs shares that may or may not exist on the network causing the boot process to appear to stall on a blank screen.

In order to mount NFS share by non-root user user may be required to be added to fstab entry. Also enable rpc-statd.service.

Create the auto_share script that will be used by cron to check if the NFS host is reachable,

/root/bin/auto_share
#!/bin/bash

SERVER="YOUR_NFS_HOST"

MOUNT_POINTS=$(sed -e '/^.*#/d' -e '/^.*:/!d' -e 's/\t/ /g' /etc/fstab | tr -s " " | cut -f2 -d" ")

ping -c 1 "${SERVER}" &>/dev/null

if [ $? -ne 0 ]; then
    # The server could not be reached, unmount the shares
    for umntpnt in ${MOUNT_POINTS}; do
        umount -l -f $umntpnt &>/dev/null
    done
else
    # The server is up, make sure the shares are mounted
    for mntpnt in ${MOUNT_POINTS}; do
        mountpoint -q $mntpnt || mount $mntpnt
    done
fi
# chmod +x /root/bin/auto_share

Create the root cron entry to run auto_share every minute:

# crontab -e
* * * * * /root/bin/auto_share

A systemd unit file can also be used to mount the NFS shares at startup. The unit file is not necessary if NetworkManager is installed and configured on the client system. See #NetworkManager dispatcher.

/etc/systemd/system/auto_share.service
[Unit]
Description=NFS automount

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/root/bin/auto_share

[Install]
WantedBy=multi-user.target

Now enable auto_share.

NetworkManager dispatcher

In addition to the method described previously, NetworkManager can also be configured to run a script on network status change.

Enable and start the NetworkManager-dispatcher service.

The easiest method for mount shares on network status change is to just symlink to the auto_share script:

# ln -s /root/bin/auto_share /etc/NetworkManager/dispatcher.d/30_nfs.sh

Or use the following mounting script that checks for network availability:

/etc/NetworkManager/dispatcher.d/30_nfs.sh
#!/bin/bash

SSID="CHANGE_ME"

MOUNT_POINTS=$(sed -e '/^.*#/d' -e '/^.*:/!d' -e 's/\t/ /g' /etc/fstab | tr -s " " | cut -f2 -d" ")

ISNETUP=$(nmcli dev wifi | \grep $SSID | tr -s ' ' | cut -f 10 -d ' ') 2>/dev/null

# echo "$ISNETUP" >> /tmp/nm_dispatch_log

if [[ "$ISNETUP" == "yes" ]]; then
    for mntpnt in ${MOUNT_POINTS}; do
        mountpoint -q $mntpnt || mount $mntpnt
    done
else
    for srvexp in ${MOUNT_POINTS}; do
        umount -l -f $srvexp &>/dev/null
    done
fi

Now when the wireless SSID "CHANGE_ME" goes up or down, the nfs.sh script will be called to mount or unmount the shares as soon as possible.

Configure NFS fixed ports

Tango-view-refresh-red.pngThis article or section is out of date.Tango-view-refresh-red.png

Reason: This section was originally refered to NFS version 3. (Discuss in Talk:NFS#)

If you have a port-based firewall, you might want to set up a fixed ports. For rpc.statd and rpc.mountd you should set following settings in /etc/conf.d/nfs-common and /etc/conf.d/nfs-server (ports can be different):

/etc/conf.d/nfs-common
STATD_OPTS="-p 4000 -o 4003"
/etc/conf.d/nfs-server
MOUNTD_OPTS="--no-nfs-version 2 -p 4002"
/etc/modprobe.d/lockd.conf
# Static ports for NFS lockd
options lockd nlm_udpport=4001 nlm_tcpport=4001

After restart nfs-common nfs-server daemons and reload lockd modules you can check used ports with following command:

$ rpcinfo -p
   program vers proto   port  service
    100000    4   tcp    111  portmapper
    100000    3   tcp    111  portmapper
    100000    2   tcp    111  portmapper
    100000    4   udp    111  portmapper
    100000    3   udp    111  portmapper
    100000    2   udp    111  portmapper
    100024    1   udp   4000  status
    100024    1   tcp   4000  status
    100021    1   udp   4001  nlockmgr
    100021    3   udp   4001  nlockmgr
    100021    4   udp   4001  nlockmgr
    100021    1   tcp   4001  nlockmgr
    100021    3   tcp   4001  nlockmgr
    100021    4   tcp   4001  nlockmgr
    100003    2   tcp   2049  nfs
    100003    3   tcp   2049  nfs
    100003    4   tcp   2049  nfs
    100003    2   udp   2049  nfs
    100003    3   udp   2049  nfs
    100003    4   udp   2049  nfs
    100005    3   udp   4002  mountd
    100005    3   tcp   4002  mountd

Then, you need to open the ports 111-2049-4000-4001-4002-4003 TCP and UDP.

Troubleshooting

There is a dedicated article NFS Troubleshooting.

See also