characteristics
(1) provide transparent file access and file transfer,
(2) easy to expand new resources or software, do not need to change the existing work environment,
3 high-performance, flexible configuration.
Editor this section evolution
Network file system (NFS) is a file system on network abstraction, to allow remote client with local file system in a similar way through the network, to visit. Although NFS not the first such systems, but it has to develop and evolve into UNIX? System is the most powerful is the most widely used network file system. NFS allowed in multiple users is Shared between public file system, and provides the data concentration of advantage, to minimize required storage space.
NFS: as usual and useful in continuing evolution
Network file system (NFS) from 1984 continued evolution since the advent, and has become the basis of distributed file system. Current, NFS (pNFS expansion by through a network of distribution of documents provide extensible visit. Explore distributed file is the principle behind, especially, recently NFS file progress.
A brief history of the NFS
The first network File system - called File Access on voicemail speak by Digital Equipment Corporation -- (DEC) in 1976 development. Data Access Protocol (DAP) implementation, this is part of the DECnet agreement sets. Such as TCP/IP, DEC for its network protocol released agreement standard, including DAP.
NFS was the first modern network file system construction in the IP protocol (above). In the early 1980s, it first as an experimental file systems, from within by Microsystems finish development. The agreement has already NFS file for that for Comments (RFC) standards and evolution is known for the NFSv2. As a standard, because NFS with other client and server interoperability and fast development.
Standard continuously evolved into NFSv3 in RFC 1813 has defined. The new agreement is better than previous versions of the expansibility and support large files (more than 2GB), and crashes will TCP as transfer protocol for file system in more widely used in network paved the road. In 2000, the RFC 3010 (revised) by 3530 RFC will NFS into enterprise Settings. From high security, introduced with state agreement before NFSv4 (NFS version are stateless). Today, NFS is version by 5661 definition (4.1 RFC), it has increased across the parallel distributed server access support (called pNFS extension).
Surprisingly, NFS has experienced almost 30 years of development. It represents a very stable (and portable) network file system, it can be expanded, high-performance, and achieve enterprise-level quality. Due to network the increased speed and delay reduced, NFS has been provided through the network file system service attractive option. Even in local network Settings, storage virtualization drive into the network, to support more mobile virtual machine. NFS even support new calculation model, to optimize the virtual infrastructure.
NFS framework
NFS allow calculation of customer -- server model (see chart 2). Server implementation Shared file system, and the client connected of storage. The client implementation user interface to share the file system, and loading to local files of space.
In Linux, virtual file system exchange (VFS) provide in a host support multiple concurrent file system method (such as cd-rom on International Standardization in ISO 9660 [for], and local hard disks of ext3fs). VFS identifying needs tend to which storage, then use which file system to meet demand. For this reason, NFS file system is with other similar can be inserted file system. For NFS speaking, the only difference is the input/output (I/O) needs are not in local meet, but need across the network to accomplish.
Once discovered for NFS specified requirements, VFS will deliver them to inside the kernel NFS examples. NFS explanation I/O request and its translation for NFS program (OPEN, ACCESS, CREATE, for, CLOSE, REMOVE, etc.). These procedures, in particular in RFC NFS file, designated the NFS in the agreement of behavior. Once from the I/O request chose program that will in remote procedure call (RPC) layer in execution. As its name suggests, RPC provides among systems implementation procedure call way. It will send NFS request, sealing and is accompanied by parameters, management will they send to appropriate distance to level, then management and tracking response, provide the appropriate requestor.
Furthmore, the mutual operation platform should include important RPC, called external data representation (XDR), it is guaranteed that when it comes to data types, all NFS participants use the same language. When given framework to execute the request, the data types may be different from said to satisfy the demands of the target host on the data type. XDR will be responsible for public type conversion said (XDR), facilitate all architecture can with Shared file system interoperability. XDR specified type bytes format (such as float) and types of byte sequence (such as repair variable-length arrays). Although XDR with its famous in the use of NFS, when you are on the public application Settings to handle multiple architecture, it is a useful norms.
Once the XDR translate the data for the public, said demand through network transmission give the transport layer protocol. Universal Datagram Protocol using NFS early (UDP), but today because its superior reliability TCP and more Universal.
In the server NFS on similar style operation. Demand reached network protocol stack, through RPC/XDR (data type conversion for server architecture) then I arrived NFS server. NFS server responsible to meet demand. Demand upward submitted to NFS daemon, it highlighted target for demand filesystem tree, and again in the local store VFS used to extract the file system. The whole process in figure 3 displays. Note that the local file server system is a typical Linux file system (such as ext4fs). Therefore, NFS not in the traditional sense file system, but access to remote file system of the agreement.
For GaoYanChi network, NFSv4 realize called compound procedure program. This a program from essentially allow in a single request embedded in multiple RPC calls, through the network request to minimize tax '. It also for response to implement the callback mode.
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