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Remote Disk Access with NFS

Remote Disk Access with NFS. Vicki Insixiengmay Jonathan Krieger. 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

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Remote Disk Access with NFS

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  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 • 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 #/etc/exports /public 134.198.161.101(rw, sync, no_root_squash) /public 134.198.161.102(rw, sync, no_root_squash) /public 134.198.161.103(rw, sync, no_root_squash) /public 134.198.161.104(rw, sync, no_root_squash) /public 134.198.161.254(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 134.198.161.103 host 134-198-161-103.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 134.198.161.103:/public /home ls /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… • 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 • Running FreeBSD • Inserted into rc.conf file nfs_client_enable = “YES” • Source http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/network-nfs.html

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

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