Dokumentace systému SUSE Linux Enterprise Desktop › Administration Guide › Services › Sharing File Systems with NFS
ContentsContents
Administration Guide
  1. About This Guide
  2. I Common Tasks
    1. 1 Bash and Bash Scripts
    2. 2 sudo
    3. 3 YaST Online Update
    4. 4 YaST in Text Mode
    5. 5 Managing Software with Command Line Tools
    6. 6 System Recovery and Snapshot Management with Snapper
    7. 7 Remote Access with VNC
    8. 8 File Synchronization
    9. 9 GNOME Configuration for Administrators
  3. II System
    1. 10 32-Bit and 64-Bit Applications in a 64-Bit System Environment
    2. 11 Booting a Linux System
    3. 12 The Boot Loader GRUB 2
    4. 13 UEFI (Unified Extensible Firmware Interface)
    5. 14 The systemd Daemon
    6. 15 journalctl: Query the systemd Journal
    7. 16 Basic Networking
    8. 17 Printer Operation
    9. 18 The X Window System
    10. 19 Accessing File Systems with FUSE
    11. 20 Dynamic Kernel Device Management with udev
    12. 21 Live Patching the Linux Kernel Using kGraft
    13. 22 Special System Features
  4. III Services
    1. 23 Time Synchronization with NTP
    2. 24 Sharing File Systems with NFS
    3. 25 Samba
    4. 26 On-Demand Mounting with Autofs
  5. IV Mobile Computers
    1. 27 Mobile Computing with Linux
    2. 28 Using NetworkManager
    3. 29 Power Management
  6. V Troubleshooting
    1. 30 Help and Documentation
    2. 31 Gathering System Information for Support
    3. 32 Common Problems and Their Solutions
  7. A Documentation Updates
  8. B An Example Network
  9. C GNU Licenses
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Dokumentace systému SUSE Linux Enterprise Desktop › Administration Guide › Services › Sharing File Systems with NFS
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Applies to SUSE Linux Enterprise Desktop 12 SP2

24 Sharing File Systems with NFS

Abstract

Distributing and sharing file systems over a network is a common task in corporate environments. The well-proven network file system (NFS) works with NIS, the yellow pages protocol. For a more secure protocol that works with LDAP and Kerberos, check NFSv4 (default). Combined with pNFS, you can eliminate performance bottlenecks.

NFS with NIS makes a network transparent to the user. With NFS, it is possible to distribute arbitrary file systems over the network. With an appropriate setup, users always find themselves in the same environment regardless of the terminal they currently use.

24.1 Terminology
24.2 Installing NFS Server
24.3 Configuring Clients
24.4 For More Information

24.1 Terminology

The following are terms used in the YaST module.

Exports

A directory exported by an NFS server, which clients can integrate it into their system.

NFS Client

The NFS client is a system that uses NFS services from an NFS server over the Network File System protocol. The TCP/IP protocol is already integrated into the Linux kernel; there is no need to install any additional software.

NFS Server

The NFS server provides NFS services to clients. A running server depends on the following daemons: nfsd (worker), idmapd (user and group name mappings to IDs and vice versa), statd (file locking), and mountd (mount requests).

NFSv3

NFSv3 is the version 3 implementation, the “old” stateless NFS that supports client authentication.

NFSv4

NFSv4 is the new version 4 implementation that supports secure user authentication via kerberos. NFSv4 requires one single port only and thus is better suited for environments behind a firewall than NFSv3.

The protocol is specified as http://tools.ietf.org/html/rfc3530.

pNFS

Parallel NFS, a protocol extension of NFSv4. Any pNFS clients can directly access the data on an NFS server.

24.2 Installing NFS Server

For installing and configuring an NFS server, see the SUSE Linux Enterprise Server documentation.

24.3 Configuring Clients

To configure your host as an NFS client, you do not need to install additional software. All needed packages are installed by default.

24.3.1 Importing File Systems with YaST

Authorized users can mount NFS directories from an NFS server into the local file tree using the YaST NFS client module. Proceed as follows:

Procedure 24.1: Importing NFS Directories

  1. Start the YaST NFS client module.

  2. Click Add in the NFS Shares tab. Enter the host name of the NFS server, the directory to import, and the mount point at which to mount this directory locally.

  3. When using NFSv4, select Enable NFSv4 in the NFS Settings tab. Additionally, the NFSv4 Domain Name must contain the same value as used by the NFSv4 server. The default domain is localdomain.

  4. To use Kerberos authentication for NFS, GSS security must be enabled. Select Enable GSS Security.

  5. Enable Open Port in Firewall in the NFS Settings tab if you use a Firewall and want to allow access to the service from remote computers. The firewall status is displayed next to the check box.

  6. Click OK to save your changes.

The configuration is written to /etc/fstab and the specified file systems are mounted. When you start the YaST configuration client at a later time, it also reads the existing configuration from this file.

Tip
Tip: NFS as a Root File System

On (diskless) systems where the root partition is mounted via network as an NFS share, you need to be careful when configuring the network device with which the NFS share is accessible.

When shutting down or rebooting the system, the default processing order is to turn off network connections, then unmount the root partition. With NFS root, this order causes problems as the root partition cannot be cleanly unmounted as the network connection to the NFS share is already not activated. To prevent the system from deactivating the relevant network device, open the network device configuration tab as described in Section 16.4.1.2.5, “Activating the Network Device”, and choose On NFSroot in the Device Activation pane.

24.3.2 Importing File Systems Manually

The prerequisite for importing file systems manually from an NFS server is a running RPC port mapper. The nfs service takes care to start it properly; thus, start it by entering systemctl start nfs as root. Then remote file systems can be mounted in the file system like local partitions using mount: 

mount host:remote-pathlocal-path

To import user directories from the nfs.example.com machine, for example, use: 

mount nfs.example.com:/home /home

24.3.2.1 Using the Automount Service

The autofs daemon can be used to mount remote file systems automatically. Add the following entry to the /etc/auto.master file: 

/nfsmounts /etc/auto.nfs

Now the /nfsmounts directory acts as the root for all the NFS mounts on the client if the auto.nfs file is filled appropriately. The name auto.nfs is chosen for the sake of convenience—you can choose any name. In auto.nfs add entries for all the NFS mounts as follows: 

localdata -fstype=nfs server1:/data
nfs4mount -fstype=nfs4 server2:/

Activate the settings with systemctl start autofs as root. In this example, /nfsmounts/localdata, the /data directory of server1, is mounted with NFS and /nfsmounts/nfs4mount from server2 is mounted with NFSv4.

If the /etc/auto.master file is edited while the service autofs is running, the automounter must be restarted for the changes to take effect with systemctl restart autofs.

24.3.2.2 Manually Editing /etc/fstab

A typical NFSv3 mount entry in /etc/fstab looks like this: 

nfs.example.com:/data /local/path nfs rw,noauto 0 0

For NFSv4 mounts, use nfs4 instead of nfs in the third column: 

nfs.example.com:/data /local/pathv4 nfs4 rw,noauto 0 0

The noauto option prevents the file system from being mounted automatically at start-up. If you want to mount the respective file system manually, it is possible to shorten the mount command specifying the mount point only: 

mount /local/path
Note
Note: Mounting at Start-Up

If you do not enter the noauto option, the init scripts of the system will handle the mount of those file systems at start-up.

24.3.3 Parallel NFS (pNFS)

NFS is one of the oldest protocols, developed in the '80s. As such, NFS is usually sufficient if you want to share small files. However, when you want to transfer big files or large numbers of clients want to access data, an NFS server becomes a bottleneck and significantly impacts on the system performance. This is because of files quickly getting bigger, whereas the relative speed of your Ethernet has not fully kept up.

When you request a file from a “normal” NFS server, the server looks up the file metadata, collects all the data and transfers it over the network to your client. However, the performance bottleneck becomes apparent no matter how small or big the files are:

  • With small files most of the time is spent collecting the metadata.

  • With big files most of the time is spent on transferring the data from server to client.

pNFS, or parallel NFS, overcomes this limitation as it separates the file system metadata from the location of the data. As such, pNFS requires two types of servers:

  • A metadata or control server that handles all the non-data traffic

  • One or more storage server(s) that hold(s) the data

The metadata and the storage servers form a single, logical NFS server. When a client wants to read or write, the metadata server tells the NFSv4 client which storage server to use to access the file chunks. The client can access the data directly on the server.

SUSE Linux Enterprise supports pNFS on the client side only.

24.3.3.1 Configuring pNFS Client With YaST

Proceed as described in Procedure 24.1, “Importing NFS Directories”, but click the pNFS (v4.1) check box and optionally NFSv4 share. YaST will do all the necessary steps and will write all the required options in the file /etc/exports.

24.3.3.2 Configuring pNFS Client Manually

Refer to Section 24.3.2, “Importing File Systems Manually” to start. Most of the configuration is done by the NFSv4 server. For pNFS, the only difference is to add the minorversion option and the metadata server MDS_SERVER to your mount command: 

mount -t nfs4 -o minorversion=1 MDS_SERVER MOUNTPOINT

To help with debugging, change the value in the /proc file system: 

echo 32767 > /proc/sys/sunrpc/nfsd_debug
echo 32767 > /proc/sys/sunrpc/nfs_debug

24.4 For More Information

In addition to the man pages of exports, nfs, and mount, information about configuring an NFS server and client is available in /usr/share/doc/packages/nfsidmap/README. For further documentation online refer to the following Web sites:

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