nfs
DESCRIPTION
TRANSCRIPT
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