Network File SystemNetwork File System (NFS)(NFS)

Submitted To: Submitted To: Rachana KamaliyaRachana KamaliyaPPresented Byresented By: Krupa Shingala: Krupa Shingala

Index

What is File System?What is Network File System?Version of NFSNFS ArchitectureAdvantages of NFSDisadvantages of NFSConclusionReferences

What is File System?

• A file system is a hierarchical structure (file tree) of files and directories.

• This file tree uses directories to organize data and programs into groups, allowing the management of several directories and files at one time.

• Some tasks are performed more efficiently on a file system than on each directory within the file system.

What is Network File System? What is Network File System?

• NFS developed by SUN Microsystems for use on its UNIX-based workstations.

• A distributed file system

• Allows users to access files and directories located on remote computers

• But, data potentially stored on another machine.

• NFS builds on the Open Network Computing Remote Procedure Call (ONC RPC) system

Continue…Continue…Mechanism for storing files on a network.

Allows users to ‘Share’ a directory.

NFS most commonly used with UNIX systems.

Other software platforms:-Mac OS, Microsoft Windows, Novell NetWare, etc.

Major Goals:-simple crash recovery

-reasonable performance :80% of a local drive

Versions and VariationsVersion 1 and Version 2

V1 Sun used only for in-house experimental purposesDid not release it to the publicV2 of the protocol originally operated entirely over UDP and was meant to keep the protocol stateless, with locking (for example) implemented outside of the core protocol.Both suffered from performance problemsBoth suffered from security problems

security dependant upon IP address

Version 3NFS v3 can operate across TCP as well as UDP

Support for asynchronous writes on the server

Obtains multiple file name, handles and attributes

Support for 64-bit file sizes and offsetsHandle files larger than 4 gigabytes (GB)

Improves performance, and allowed it to work more reliably across the Internet

Version 4Currently version 2 and version 3 protocols are in use with version 4 under consideration for a standardincludes more performance improvementsMandates strong security

introduces a stateful protocol

developed with the IETF (Internet Engineering Task Force)

File System

File System

NFS Client

NFS Client

Network NFS Server File System

NFS Architecture

RPC request Action

CREATE Creates (or truncates) a file in the directory

LINK Creates a hard link

LOOKUP Looks up a file in the directory

MKDIR Makes a directory

READADDR Reads the contents of a directory

REMOVE Removes a file in the directory

RENAME Renames a file in the directory

RMDIR Removes a directory

SYMLINK Creates a symbolic link

NFS Protocol

RPC request Action

GETATTR Get file attribute

SETATTR Set file attribute

LOOKUP File name search

ACCESS Check access

READ Read file

WRITE Write to the file

CREATE Create file

REMOVE Remove file

RENAME Rename file

stateless server and client server can be rebooted and user on client might be unaware of the rebootclient/server distinction occurs at the application/user level not the system level highly flexible, so we need to be disciplined in our administration/configuration

Advantages

Disadvantage

uses RPC authenticationeasily spoofed

filesystem data is transmitted in cleartextData could be copied

Network slower than local disk

Complexity, Security issues.

Conclusion

New technologies open up new possibilities for network file systems Cost of increased traffic over Ethernet may cause problems for xFS, cooperative caching.

References

www.compnetworking.comwww.internetslang.comwww.linux.com