mogeneous in terms of the operating system, data representation, and executable program format. Therefore it is often the case that distributed object systems contain additional overheads that are not necessary on Beowulf clusters. In the future, we may see distributed objects tailor their implementations for high performance on Beowulf-like systems as the use of PC clusters becomes more common in corporate computing.
5.6 Distributed File Systems
Every node in a Beowulf cluster equipped with a hard drive has a local file system that processes running on other nodes may want to access. Even diskless internal nodes at least require access to the worldly node's file system so that they may boot and execute programs. The need for inter-node file system access requires Beowulf clusters to adopt one or more distributed file systems. Most distributed file systems possess the following set of characteristics that make them appear indistinguishable from the local file system.
Network Transparency Remote files can be accessed using the same operations or system calls that are used to access local files.
Location Transparency The name of a file is not bound to its network location. The location of the file server host is not an intrinsic part of the file path.
Location Independence When the physical location of a file changes, its name is not forced to change. The name of the file server host is not an intrinsic part of the file path.
5.6.1 NFS
Beowulf clusters almost always use the Network File System (NFS) protocol to provide distributed file system services. NFS started its steady climb in popularity in 1985, after Sun Microsystems published the protocol specification for adoption as an open standard. This version of the protocol, NFS version 2 (NFSv2), has been widely adopted by every major version of the Unix operating system. A later revision of the protocol, NFSv3, was published in 1993, and has been implemented by several vendors, but as of early 1999, it is not supported as standard Linux software. The standard Linux NFS software still conforms to the NFSv2 specification.
NFS is structured as a client/server architecture, using RPC calls to communicate between clients and servers. The server exports files to clients which access the files
