Remote File Sharing (RFS) is a

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ...

operating system component for sharing resources, such as files, devices, and file system directories, across a network, in a network-independent manner, similar to a

distributed file system A clustered file system is a file system which is shared by being simultaneously mounted on multiple servers. There are several approaches to clustering, most of which do not employ a clustered file system (only direct attached storage for ...

. It was developed at

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in the 1980s, and was first delivered with

UNIX System V Unix System V (pronounced: "System Five") is one of the first commercial versions of the Unix operating system. It was originally developed by AT&T and first released in 1983. Four major versions of System V were released, numbered 1, 2, 3, an ...

Release 3 (SVR3). RFS relied on the STREAMS Transport Provider Interface feature of this operating system. It was also included in UNIX System V Release 4, but as that also included the

Network File System Network File System (NFS) is a distributed file system protocol originally developed by Sun Microsystems (Sun) in 1984, allowing a user on a client computer to access files over a computer network much like local storage is accessed. NFS, like ...

(NFS) which was based on

TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...

and more widely supported in the computing industry, RFS was little used. Some licensees of AT&T UNIX System V Release 4 did not include RFS support in SVR4 distributions, and

Sun Microsystems Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, the ...

removed it from

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2.4.

Features

The basic application architecture of RFS is the

client–server model The client–server model is a distributed application structure that partitions tasks or workloads between the providers of a resource or service, called servers, and service requesters, called clients. Often clients and servers communicate over ...

, in which a participating host may be a server as well as a client, simultaneously. It was based on different design decisions, in comparison to the Network File System (NFS). Instead of focusing on reliable operation in the presence of failures, it focused on preserving UNIX file system semantics across the network. This enabled the system to provide remote access to hardware resources located on an RFS server. Unlike NFS (before version 4), the RFS

server Server may refer to: Computing *Server (computing), a computer program or a device that provides functionality for other programs or devices, called clients Role * Waiting staff, those who work at a restaurant or a bar attending customers and su ...

maintains state to keep track of how many times a file has been opened, or the

locks Lock(s) may refer to: Common meanings *Lock and key, a mechanical device used to secure items of importance *Lock (water navigation), a device for boats to transit between different levels of water, as in a canal Arts and entertainment * ''Lock ...

established on a file or device. RFS provides complete UNIX/POSIX file semantics for all file types, including special devices, and named pipes. It supports access controls and record and

file locking File locking is a mechanism that restricts access to a computer file, or to a region of a file, by allowing only one user or process to modify or delete it at a specific time and to prevent reading of the file while it's being modified or deleted ...

of remote files in a transparent manner as if the shared files are local. This permitted binary application compatibility when involving network resources. It allows the mounting of devices across the network. For example, ''/dev/cdrom'' can be accessed remotely, as if it were a local resource. Access to any specific file or a file system directory is transparent across the network, so that users do not need to know where a file is actually located. RFS is implemented independently of the underlying network technology. For this it relies on the System V STREAMS mechanism using the Transport Provider Interface.Dennis M. Ritchie, ''A Stream Input-Output System'', Bell Laboratories Technical Journal 63(8) (October 1984)

Remote system call interface

* ACCESS * SYSACCT * CHDIR Change directory * CHMOD Change file mode * CHOWN Change file owner * CHROOT * CLOSE Close a file * CREAT Create a file * EXEC Execute a file * EXECE Execute a file with an environment * FCNTL * FSTAT Stat a file using a

file descriptor In Unix and Unix-like computer operating systems, a file descriptor (FD, less frequently fildes) is a process-unique identifier (handle) for a file or other input/output resource, such as a pipe or network socket. File descriptors typically have ...

* FSTATFS Stat a file system using a file descriptor * IOCTL * LINK First half of link() operation * LINK1 Second half of link() operation * MKNOD Make block or character special file * OPEN Open a file * READ Read from a file * SEEK Seek on a file * STAT Stat a file using pathname * STATFS Stat a file system using pathname * UNLINK * UTIME * UTSSYS Return information about a mounted files * WRITE * GETDENTS Read directory entries in a file system * MKDIR * RMDIR * SRMOUNT Server side of remote mount * SRUMOUNT Server side of remote unmount * COREDUMP Dump core request * WRITEI Internal form of write system call * READI Internal form of read system call * RSIGNAL Sendremote signal * SYNCTIME Synchronize time between machines * IPUT Free a remote inode * IUPDATE Update a remote inode * UPDATE Write modified buffers back to disk.

References

Internet protocols Network file systems Internet Protocol based network software UNIX System V {{Compu-storage-stub

Features

Remote system call interface

See also

References