Alternatives Of Network File System Essay Research

Paper

CONTENTS OF THE REPORT

List of contents???????????????.. 1

The introduction??????????????? 2

Sun Microsystems provides NFS version 4 ???? 5

The relation between the NFS server and

Client file systems?????????????? 6

Architecture of NFS????????????? 8

Alternative for NFS????????????? 9

What is CIFS (SMP)????..???????? 9

SMB Clients and Servers Currently

Available ????????????????? 10

comparison between NFS and CIFS(SMP)???????????????? 11

Conclusion????????????????. 15

Bibliography???????????????.. 17

Introduction

Since human beings have used Computers , the request of being rich ,and getting more information quicker than before has increased . Have you ever found yourself rushing from one computer to another in your office or home ,attending to several different jobs at various location? Or do you often find yourself moving files that need printing from a PC that you happen to be working on the PC that is Connected to the printer ?

You may have heard a lot about the advantages of using the internet for sending e-mail, and decided that you want to get connected .

Or perhaps you are already connected to the internet through a single PC/Modem , but want all of your office colleagues to have access .

All of these situations can be made easier by allowing the various machines to communicate with each other ? by networking the PCs but sometime you don?t know that your PC has (NFS) operating system for sharing file systems and directories across TCP/IP – based Networks.

Network File System (NFS) is a popular network operating system and it?s a distributed file system that allows users to access files and directories located on remote Computers and treat those files and directories as if they were local. For example, users can use operating system commands to create, remove, read write and set files attributes for remotes files and directories.

NFS was first introduced by Sun Microsystems in the early 1980s and was quickly adopted as de facto standard for sharing files and printers between UNIX system. This standard was extended to include PCs and became the basis for must transparent file and print connectivity software solutions . Examples of using NFS

Creating a /usr/local environment in a multi architecture environment. Some directories such as man and doc are architecture neutral, others such as bin and lib are architecture specific.

Creating a rational user file system, when users have files located on their specific machines NFS can be used to make it look coherent on the server.

Creating a central mail spool for all users. This allows users to sign on any machine and access there mail.

In this report , I highlighted some inquires that related with NFS such as :

? Sun Microsystems provides NFS version 4

The NFS standard, which Sun created and turned over to the Internet Engineering Task Force (IETF), enables diverse operating environments to access and share remote files across the network. NFSv4 improves on four areas of the standard: security, performance, interoperability and Internet access. To provide strong security for NFS v4, implementations of the protocol must provide for the use of Kerberos V5 and Public Key Infrastructures through the use of the Low Infrastructure Public Key, LIPKEY; dynamic client response to changes on NFS servers; namespaces that are compatible across all platforms; client file caching that provides for good performance via the Internet while maintaining performance in the traditional LAN environment; and compound operations to minimize the number of connections necessary per transfer.

? The relationship between NFS server and Client file system.

NFS consists of the NFS server and the NFS client software. The NFS server is implemented as a daemon, waiting for requests from clients. The NFS server does not retain the state of the NFS client.

? Architecture of NFS.

NFS is designed to give users high performance, transparent access to server file systems on global networks. Some of the most important design principles are summarized below:

Transparent Access, Statelessness, Portability, Fast Recovery From Failure, Network Protocol Independence, Performance, Security.

? Are there any Alternative for NFS?

Other alternatives to NFS include:

- AFS — Andrew File System developed at CMU

- DFS — Distributed File System from OSF.

- RFS — Remote File System found on older V.3 versions

ofUnix.

- Netware — Novell based file system.

- CIFS — Common Internet File System

? What is CIFS (SMP) ?

CIFS defines a standard remote file system access protocol for use over the Internet, enabling groups of users to work together and share documents across the Internet or within their corporate intranets. CIFS is an open, cross-platform technology based on the native file-sharing protocols built into Microsoft? Windows? and other popular PC operating systems, and supported on dozens of other platforms, including UNIX?. With CIFS, millions of computer users can open and share remote files on the Internet without having to install new software or change the way they work.

? Technology comparison between NFS and CIFS(SMP).

In every textbook description of NFS, its statelessness is emphasized. NFS operations are idempotent (can be repeatedly applied harmlessly), or if non-idempotent (e.x., file deletion) are managed safely by the server. Clients are oblivious to server reboots (if service is restored promptly), with few exceptions. The NFS protocol emphasizes error recovery over file locking ? error recovery is simple if no state need be preserved.

A CIFS file server is not stateless. The CIFS protocol emphasizes locking over error recovery because PC application software relies on strict locking. Strict locking requires a sustained connection. It is imperative that an active session not be interrupted. Applications executing on PC clients react to a CIFS server in exactly the same manner as they do to local disk drives: a down server is no different a condition than an unresponsive disk drive. Therefore, PC clients must be warned — and allowed time — to gracefully disengage (i.e., save files, exit applications, and so on) before server shutdowns or reboots.

I have explaned similarly points between NFS and CIFS ,which to be provided in the conclusion last report .

1.1 Sun Microsystems provides NFS version 4

When the NFS protocol was designed, machines were far less powerful than today, networks were more commonly local area networks (LANs) than wide area networks (WANs), and available security mechanisms were relatively easy to exploit. Additionally, although NFS was designed to interoperate between different operating systems, many of the protocol features have favored UNIX ? file semantics. This history has led to problems in using NFS solutions over the Internet, where security, performance, and interoperability are key. Version 4 of NFS is designed to address these concerns by providing:

? Improved access and good performance on the Internet

? Strong security, with security negotiation built into the protocol

? Enhanced cross-platform interoperability

? Extensibility of the protocol

Stronger in its support of intranets and the Internet, NFS Version 4 will also provide excellent service in environments currently standardized on earlier versions of NFS. Unlike versions 2 or 3, NFS Version 4 can be an important element in the strategy of enterprises to provide better support for global networks.

Although NFS Version 4 owes its general design to previous versions of NFS, it is a self-contained protocol that does not have any dependencies on the previous versions. However, to address backward compatibility with the installed base, Versions 2, 3, and 4 can be supported concurrently. Current users of NFS Versions 2 and 3 may look forward to NFS Version 4 as a reasonable, solid migration strategy to serve their Internet and intranet distributed file system needs.

At the time of the publication of this white paper, the NFS Version 4 protocol is still under development by the IETF(1), so, the final standard may not incorporate all of the features exactly as they are described here.

However, NFS Version 4 uses a universal character set, so it doesn?t matter if the user accessing the file has a different locale than the user who created the file. This universal programming of the character makes it possible to determine what language the character is from and how to display it on the client. The server does not need to associate a locale with a pathname.

IETF(1) the IETF is an open international community with evolution of the internet architecture .As such ,it is the principal body engaged in the development of anew internet standards and procedures.

2.1 The relation between the NFS server

and Client file systems

NFS consists of the NFS server and the NFS client software. The NFS server is implemented as a daemon, waiting for requests from clients. The NFS server does not retain the state of the NFS client.

The NFS server daemon is multithreaded; it processes multiple NFS client calls, in parallel. The NFS server daemon is also an event-driven, asynchronous process. Each NFS client call contains all the information necessary to complete the request see Figure ( 1 ) .

The NFS client software implements a state mechanism that maintains all information required for processing client requests. Each client operation can be requested more than once and contains all the information necessary to complete the request. This model presumes no file open and close requests because these require saving the state of the object and that the server write data to the disk before returning the reply message to the user.

When mounting a remote file system, an NFS client sends a message that makes the remote file system part of the local file directory. The remote host redirects operations that access files on the remote file system to the NFS client software. The NFS client and NFS server then exchange messages.

Figure 1 The division of NFS between client and server

NFS Follows the Client ?server model, in which the server is the system that owns the file system resource and is configured to share it with other systems .An NFS-shareable resource is usually referred to as an exported file system. The client is the resource user .It uses the exported file system as if it were part of the local file system .To achieve this transparency, the client is said to mount the exported directory to the local file system.

In Figure(2) , /efs is the exported directory on host netrix (the NFS server). To access that directory from client jade, it must be mounted first.

To do that ,the administrator creates the /ifs directory to use as the mount directory and issues the appropriate mount command .

Consecuently, to access the file budget.rpt from host jade, the user must specify /ifs/reports/budget.rpt as the path to that file.

Figure 2 The relationship between the NFS server and client file systems.

To transparently access the file budget.rpt from host jade, the user mounts the exported directory /efs on NFS server netrix and specifies / ifs/report/budget.rpt as the path to the command.

3.1 Architecture of NFS

NFS is designed to give users high performance, transparent access to server file systems on global networks. Some of the most important design principles are summarized below:

Transparent Access: Users and applications can access remote files as if they were local. They are not required to know whether the files reside on the local disk or on remote servers.

Portability: NFS is machine and operating system independent. This allows it to be ported easily to multiple OS and hardware platforms from PCs to mainframes.

Fast Recovery From Failure: NFS is designed to recover quickly from system failures and network problems, causing minimal disruption of service to users.

Network Protocol Independence: NFS has the flexibility to run on multiple transport protocols instead of being restricted to just one. This allows it to utilize existing protocols today as well as new protocols in the future.

Performance: NFS is designed for high performance so that users can access remote files as quickly as they can access local files.

Security: The NFS architecture enables the utilization of multiple security mechanisms. This allows system administrators to choose the security mechanism that is appropriate for their distributed file sharing environment instead of being restricted to one solution. This also allows NFS to utilize new security mechanisms in the future.

These features are implemented within the NFS client/server framework which reduces costs by enabling heterogeneous resource sharing across the global enterprise. Servers make their file systems sharable through a process called exporting. Clients gain access to these file systems by adding them to their local file “tree” via the mount process. The NFS protocol provides the medium for communication between client and server processes over the network.

1.2 Alternative for NFS

Naturally ,as a mechanism ,NFS has competitors .In particular ,integration of MS_DOS systems with file servers will certainly not be achieved by equipping all PCs with PC-NFS . For examples Remote File System (RFS), Open Software Foundation?s Distributed Computing Environment includes the Distributed File System (OSF/DCE DFS ).

There are two primary methods currently used to provide PC to UNIX connectivity. The first, based on use of the Network File System (NFS) has been widely implemented since the early 1980?s. The second, newer alternative is based on using the Common Internet File System (CIFS), formerly known as SMB (Server Message Block).

SMB is an important protocol because of the large number of PCs out there that already have client and server implementations running on them. All Windows for Workgroups, Windows 95 and Windows NT systems are (or are capable of) running SMB as either a client, a server, or both.

2.2 What is CIFS (SMP)?

SMB, which stands for Server Message Block, is a protocol for sharing files, printers, serial ports, and communications abstractions such as named pipes and mail slots between computers as Figure ( 3 ) .

Figure ( 3 )

The earliest document I have on the SMB protocol is an IBM document from 1985. It is a copy of an IBM Personal Computer Seminar Proceedings from May 1985. It contains the IBM PC Network SMB Protocol. The next document I have access to is a Microsoft/Intel document called Microsoft Networks/OpenNET-FILE SHARING PROOL from 1987

3.2 SMB Clients and Servers Currently Available

There are a few SMB clients available today and a relatively large number of servers available from a range of vendors. The main clients are from Microsoft, and are included in Windows for WorkGroups 3.x, Windows 95, and Windows NT. They are most evident when you use the File Manager or the Windows 95 Explorer, as these allow you to connect to servers across the network. However they are also used when you open files using a UNC (universal naming convention).

Some other clients that I am aware of are:

? smbclient from Samba

? smbfs for Linux

? SMBlib (an SMB client library that is in development)

Server implementations are available from many sources. Some that I am aware of are:

? Samba

? Microsoft Windows for Workgroups 3.x

? Microsoft Windows 95

? Microsoft Windows NT

? The PATHWORKS family of servers from Digital

? LAN Manager for OS/2, SCO, etc

? VisionFS from SCO

? TotalNET Advanced Server from Syntax

? Advanced Server for UNIX from AT&T (NCR?)

? LAN Server for OS/2 from IBM

There are four basic things that one can do with Samba:

1. Share a Linux drive with Windows machines.

2. Access an SMB share with Linux machines.

3. Share a Linux printer with Windows machines.

4. Share a Windows printer with Linux machines.

4.2 Comparison between NFS and CIFS(SMP)

Here is how they compare from a user?s perspective.

NFS CIFS (SMB)

1 Background NFS was first introduced by Sun Microsystems in the early 1980s and was quickly adopted as the de facto standard for sharing files and printers between UNIX systems. This standard was extended to include PCs and became the basis for most transparent file and print connectivity software solutions. SMB was introduced as a PC networking standard by Microsoft in the early 1980s. It is the Microsoft native method of allowing file and print sharing among network users. Modern connectivity solutions have extended CIFS capabilities to allow UNIX systems to function as CIFS servers.

NFS CIFS (SMB)

2 Connectivity Model The NFS approach allows PCs to work within a UNIX-oriented network by adding NFS client technology to PCs. This “Windows Way” approach of CIFS allows UNIX to function as a native Windows server. This means that UNIX resources simply show up in the existing PC network.

3 Connectivity Model (continued) The NFS model requires that NFS client software be loaded on each PC on the network. A CIFS software server is simply added to any UNIX server on the network. No additional software needs to be loaded on the PCs to get transparent file and print services.

4 Connectivity Model (continued) Advantage: NFS is distributed as an extension to most versions of the UNIX operating system. Advantage: CIFS is native operating system technology in Windows 98/95, NT and Windows for Workgroups. Loading a CIFS server on any UNIX host on the network makes all network resources available to users (provided they have permission to use them).

5 Connectivity Model (continued) Disadvantage: Requiring NFS to be loaded on each PC in the network is time consuming for the System Administrator (20-30 minutes per PC to load & configure), and adds system overhead to the PC as well as the network. Also, NFS requires an invasive, kernel level installation on each PC. Even more problematic, on-going maintenance and updates must continue to be installed on each PC.

NFS CIFS (SMB)

6 Performance Issues NFS is available in almost as many variations as UNIX itself. Each vendor who supplies NFS as an extension to their UNIX operating system or as an add-on to work with their TCP/IP stack, generally provides an NFS solution that is optimized based on their view of how their NFS product will be used by customers. Therefore, it is difficult to make sweeping statements about the performance of NFS as a technology without discussing individual implementations. To be sure, most are adequate for the purposes of file and printer sharing. However, NFS does have some limiting characteristics regardless of vendor implementation: CIFS was developed as part of the networking architecture of the Windows operating system by Microsoft. CIFS (or SMB) has been included in all versions of Windows and has become the new standard for cross-platform connectivity. When CIFS is added to a UNIX server, all of its resources become transparently available to each PC user on the network. Using a CIFS server as opposed to NFS clients does address some of the performance limiting factors of NFS:

7 Performance Issues (continued) PC Resources: All NFS solutions require that NFS be loaded on each PC in the network. This creates a resource issue for System Administrators because very few users can install and configure NFS for themselves. Since NFS is required to run on the PC, it also affects PC system resources by requiring additional CPU cycles, memory & disk resources. PC Resources: Since no additional software is required on the PC, the system administrator’s primary task is to load and configure the CIFS server on the UNIX system. In most implementations, this requires about 10-20 minutes, or roughly the time required to load NFS on a single PC. A significant difference to a system administrator with hundreds of networked PCs. While the TCP/IP network must still be configured on the PC, this is a relatively easy task done with native Windows software.

8 Performance Issues (continued) Synchronous: Most NFS implementations use a Synchronous data transfer method. This means that only one write operation can be accomplished at a time. Each write operation must be completed before another can begin. Asynchronous: CIFS allows for Asynchronous writes, meaning that multiple disk writes can be requested simultaneously.

9 Performance Issues (continued) Reliability: Customers of PC-based NFS networks have long complained of PC and network “lockups.” Reliability: The CIFS network is not plagued with these “lockup” problems.

NFS CIFS (SMB)

10 Network Management In an NFS-based approach, network management becomes more complex as each new PC is added. Additionally, most NFS-based connectivity solutions bundle additional applications (such as Email clients, ftp client, etc.) which add administrative complexity each time the product is upgraded. The CIFS server requires about 6MB of disk space on the server and takes about 10-20 minutes to install and configure. For file and print services, no software is required on any of the PCs. The CIFS-based approach is considerably more network management friendly in terms of the resources needed for installation and ongoing maintenance. CIFS also requires no change to the network drivers on either end (server or client) of the network.

Conclusion

? NFS fully satisfies enterprise requirements for global file sharing. It supports global workgroups by keeping file systems located worldwide continuously and transparently accessible to users. An industry leader in performance, NFS provides fast access to file information as well as the scalability to support small to large network environments. Because it relies on a flexible and extensible security architecture, it enables administrators to choose the security solution that fits their environment today and to have more options in the future. The ability to administer NFS centrally reduces the time and effort it takes to perform a variety of routine administration tasks. Finally, for mission critical environments, a highly available NFS implementation is provided. These features together with the vast array of multi-vendor NFS products to choose from and a rapidly growing licensee and installed base, reaffirm that NFS is the right choice for integrating the heterogeneous enterprise both now and in the future.

? Solstice Network Client’s NFS software was designed for complete integration with all Microsoft Windows platforms – Windows NT, Windows 95, Windows 3.1 and Windows for Workgroups 3.11. Your users retain their familiar Microsoft Windows interface and continue to work with point and click ease.

? “The increased eight-way SMP support in Windows 2000 Advanced Server complements the reliability and scalability features of the new eight-way HP NetServer LXr 8500 system,” said Eileen O’Brien, marketing manager, Hewlett-Packard Network Server Division. “The powerful combination of Windows 2000 and the HP NetServer systems will enable our enterprise customers to optimize performance by providing best-in-class power, investment protection and intelligent management. By increasing the SMP support in each of the Windows 2000 Server products, Microsoft is supporting the shift to higher end servers that are powerful, versatile and fast enough to handle the demands of large enterprises,” said Sandy Carter, director, PartnerWorld for Developers, Netfinity Brand at IBM. “The eight-way SMP support in Windows 2000 Advanced Server and the Netfinity 8500R will provide customers with a solution that maximizes uptime and provides superior manageability for compute-intensive business intelligence, transaction processing and server consolidation projects while providing a great value in eight-way servers.”

- Nance,B. (1997) Introduction to Networking, Forth Edition, by

Que? Corporation. Pages 231,235

- Heath,S. (1993) Effective PC Networking, First Edition , by An imprint

of Butterworth ?Heinmann Ltd. Page 102.

- Santifaller,M. (1994) TCP / IP and ONC / NFS , Second Edition ,by Addison-Wesley. Pages from 134 to 137.

- Douba,S. (1998) Networking Unix the complete reference for Unix

networks, Forth Edition, by Sams Publishing . Pages 302,314,320.

Websites References

? http://www.netapp.com/tech_library/3014.html

? http://www.ietf.org/proceedings /99jul/l-d/draft-ietf-nfsv4-requirements-03.text.

? http://www.facetcorp.com/competition_nfs_cifs comparison.html

? http://www.sun.com/smi/press/sunfash/2000- 02/sunflash.20000202.2.html

? http://msdn.microsoft.com/worshop/networking/CIFS/default.asp

? http://www.sun.com/software/white-papers/wp-nfs/nfs_9.html

? http://nscp.upenn.edu/aix4.3html/aixbman/commadmn/nfs_intro

html

? http://www.linuxdoc.org/HOWTO/SMB-HOWTO.html

? http://windowsitlibrary.com/Content/172/01/26.html

? Portfolio of report :

Reference No : 1

Reference name : Nance,B. (1997) Introduction to Networking, Forth

Edition, by Que? Corporation.

Titles: general information about NFS page 231 ,NFS and protocols

(TCP/IP) page 235.

Reference No : 2

Reference name : Heath,S. (1993) Effective PC Networking, First

Edition , by An imprint of Butterworth ?Heinmann Ltd.

Titles: general information about NFS and how the NFS accesses in

Networks . page 102 .

Reference No : 3

Reference name : Santifaller,M. (1994) TCP / IP and ONC / NFS ,

Second Edition ,by Addison-Wesley.

Titles: The first types of protocols and how are developed and some

alternative to NFS Pages from 134 to137.

Reference No : 4

Reference name: Douba,S. (1998) Networking Unix the complete

reference for Unix

networks, Forth Edition, by Sams Publishing .

Titles: Network File system: Concept and Setup and the relation

between NFS server and C file system and also Architecture of

NFS and is NFS for Unix only! . Pages 302,314,320.

Reference No : 5

Website Address: http://www.netapp.com/tech_library/3014.html

Titles: General information about NFS and CIFS(SMP) and give us

some the common points between them, and NFS vs CIFS,

Multiprotocol file service .

Reference No : 6

Website Address: http://www.ietf.org/proceedings /99jul/l-d/draft-ietf-

nfsv4-requirements-03.text.

Titles: The deferent between NFS v4 NFS v3,v2 ,and what is the new in

NFS v4 .

Reference No : 7

Website Address: http://www.facetcorp.com/competition_nfs_cifs

comparison.html

Titles: Comparison NFS and CIFS (SMP ) .

Reference No : 8

Website Address: http://www.sun.com/smi/press/sunfash/2000-

02/sunflash.20000202.2.html

Titles : Sun Microsystems gives key Component of NFS to the open

source community, and provide NFS version 4 solutions .

Reference No : 9

Website Address: http://www.sun.com/software/white-papers/wp-

nfs/nfs_9.html

Titles : History of NFS from the past until now.

Reference No : 10

Website Address: http://msdn.microsoft.com/worshop/networking/CIFS

/default.asp

Titles : CIFS An internet File System Protocol ,Microsoft is making sure

that CIFS tech is open ,published, and widely available for all

computer users

Reference No : 11

Website Address : http://nscp.upenn.edu/aix4.3html/aixbman/commadmn

html

Titles : NFS overview ,AIX supports the latest NFS protocol update .

Reference No : 12

Website Address : http://www.linuxdoc.org/HOWTO/SMB-

HOWTO.html

Titles : The SMP protocol is used by Microsoft , What is the SAMA?.

there are four basic things that one can do with samba .

Reference No : 13

Website Address : http://windowsitlibrary.com/Content/172/01/26.html

Titles : NFS in action , NFS comes to Windows NT , inter the PC.