1. Remote Disk Access with NFS
Vicki Insixiengmay
Jonathan Krieger

2. NFS Background Developed inside Sun Microsystems in early 1980’s
Based on 2 similar but distinct protocols
MOUNT  Initial Negotiation between Server and Client
Determines which file systems are available for mounting
NFS  Allows Client to Utilize Files in Directory

3. NFS Description Network File System(NFS)
An abbreviation for Network File System, a file format and set of drivers created by Sun Microsystems Incorporated that allows DOS/Windows and UNIX applications to share files on disk drives running under UNIX. NFS relies on remote procedure calls (RPCs) for communication between clients and servers.
Allows any network user to access disk space over a networks.
Incorporates with NIS to access specific file folders for each user

4. Important NFS Concepts
Virtual File System (VFS) – transparently and automatically redirects for mounted files to the server
Remote Procedure Call (RPC) – used for background mounting of a folder with a file system
Hard Mounting – Continuously trying to remount a file system
Soft Mounting – Repeated RPC failures cause the NFS to fail and not hang

5. Important NFS Daemons
portmap – manages connections for applications that use the RPC specification
nfs – starts necessary RPC processes
nfslock – allows clients to lock files within the NFS file system
netfs – allows processes running on the client to mount an NFS file system

6. Installing NFS RedHat Linux installs NFS by default To check:
Automatically activated when system boots
To check:
rpm –qa | grep nfs
If list is empty, one needs to installed

7. Configuring NFS on the Server
Needs
portmap
nfs
nfslock
Correctly configured /etc/exports file

8. Configuring the /etc/exports file
Main NFS configuration file
2 columns:
1st  Directories made available on the network
2nd  Networks or DNS domains that can access the directories and options
Options include:
ro, rw, no_root_squash, no_subtree_check, sync

9. The /etc/exports file NFS Users Control Panel in Linux #/etc/exports
/public (rw, sync, no_root_squash)
/public (rw, sync, no_root_squash)
/public (rw, sync, no_root_squash)
/public (rw, sync, no_root_squash)
/public (rw, sync, no_root_squash)
NFS Users Control Panel in Linux

10. Starting NFS on the Server
Configure required daemons
chkconfig –level 35 nfs on
chkconfig –level 35 nfslock on
chkconfig –level 35 portmap on
Use /etc/init.d to start daemons
service portmap start
service nfs start
service nfslock start
Test NFS
rpcinfo –p localhost

11. Starting NFS on the Client
Configure required daemons
chkconfig –level 35 netfs on
chkconfig –level 35 nfslock on
chkconfig –level 35 portmap on
Use /etc/init.d to start daemons
service portmap start
service netfs start
service nfslock start
Test NFS
rpcinfo –p

12. NFS and DNS
NFS client must have a matching pair of forward and reverse DNS entries
DNS lookup on NFS server for IP address of NFS client must return server name mapping back to original IP address
host
host research.cs.uofs.edu

13. NFS Directory Mounting -- Permanent
Insert line into /etc/fstab file
#/etc/fstab
#Directory Mount Point Type Options Dump FSCK
.103:/public /home nfs defaults 0 0
Create mount directory
mkdir /home
Mount onto directory into new directory
mount -a

14. NFS Directory Mounting -- Temporary
No needed /etc/fstab entry
mkdir /home
ls /home
mount –t nfs :/public /home
<Listing of Directory>

15. Deleting a Share Removing an exported directory from /etc/exports
Client Side:
umount /home
Server Side:
Exportfs –ua
Exportfs -a

16. Problems After installing NFS on lab3… Errors Firewall Problems
Lab3  mounted
Others  NFS on
Errors
port 22: No route to host
Permission denied, server is down
Firewall Problems

17. Problems Installing NFS on Gateway Source Running FreeBSD
Inserted into rc.conf file
nfs_client_enable = “YES”
Source

18. References www.linuxdocs.org www.linuxhomenetworking.com