Network File SystemOutlineIntroductionClients and serversDistributionTransparencyPerformanceConcurrent File UpdatesDistributed Data StoreDistributed Data-Store NetworksWindows Distributed File SystemsWhat is the purpose of Windows DFS?ComparisonDFS File ProtocolsHistorySolution to historical problemsDFS Features and BenefitsDFS Features and Benefits (Continued)Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27AdministrationAdministration (Continued)User ViewLoad BalancingName TransparencyTechnical Overview of DFSPost-Junction JunctionsPost-Junction Junctions (Continued)ExampleExample (Continued)Alternate VolumesDown-Level VolumesPartition Knowledge Table (PKT)IllustrationResolving JunctionsSlide 43Fail over to between volumesFail-over Scenario 1Fail-over Scenario 2Fail-over Scenario 3Fail-over Scenario 4SecurityAdministered at each physical shareNetwork File SystemNFS Architecture (1)NFS Architecture (2)Important Advantage Of NFSFile System ModelFile HandlesProcessesStateful ApproachCommunicationNaming (1)Naming (2)Automounting (1)Automounting (2)File AttributesSlide 65Semantics of File Sharing (1)Semantics of File SharingFile Locking in NFS (1)Client Caching (1)Client Caching (2)RPC FailuresSlide 72Secure RPCsAccess ControlBenchmarking studyOutlineNFS ArchitecturePerformance Study DesignNFS ParametersSystem SoftwareClearcacheExperimental ParametersExperimental ResultsNFS, LWF and GWF with and without server readingPVFS UNIX/POSIX API compared to NFSPVFS and NFS, GWF, 1 and 2 clients with/without server participatingConclusionsNetwork File SystemPhil SegelMuhammad Kamran ArainAla F. AlnawaisehGroup 3OutlineIntroductionNetwork File System (NFS)Windows Distributed File System (DFS)IntroductionA Distributed File System (DFS): is a File System, that supports sharing of files and resources in the form of persistent storage over a network. The first file servers were developed in the 1970s.Sun’s Network File System (NFS) became the first widely used distributed file system after its introduction in 1985.Clients and serversA file server provides file services to clients.A client interface for a file service is formed by a set of primitive file operations:–Creating a file.–Deleting a file.–Reading from a file.–and Writing to a file.DistributionA DFS is a file system whose clients, servers, and storage devices are dispersed among the machines of a Distributed System or intranet. Accordingly, service activity has to be carried out across the network, and instead of a single centralized data repository, the system has multiple and independent storage devices. The distinctive features of a DFS are the multiplicity and autonomy of clients and servers in the system.TransparencyIdeally, a DFS should appear to its clients to be a conventional, centralized file system. The multiplicity and dispersion of its servers and storage devices should be made invisible.PerformanceThe most important performance measurement of a DFS is the amount of time needed to satisfy service requests. –In conventional systems, this time consists of a disk-access time and a small amount of CPU-processing time. –In a DFS, however, a remote access has the additional overhead attributed to the distributed structure.Concurrent File UpdatesA DFS should provide for multiple client processes on multiple machines not just accessing but also updating the same files.Concurrency control or locking may be either built into the file system or be provided by an add-on protocolDistributed Data StoreA Distributed Data Store is a network in which a user stores his or her information on a number of peer network nodes. Most of the peer to peer networks do not have distributed data stores in that the user's data is only available when their node is on the network.Distributed Data-Store NetworksFreeNet.MNet.Andrew File System (AFS).NNTP.BitTorrent The Mnesia Database.GNUnet. Secure File system (SFS)Global File System (GFS) The Chord Project.SVK – Distributed Version Control.Groove shared workspace, used for DoHyki.Windows Distributed File SystemsWhat is the purpose of Windows DFS?To unite files on different computers into a single namespaceMake it easy to build a single, hierarchal view of multiple file servers and file server shares on your networkTo display files in a single directory structure regardless of what server the files are onComparisonWindows Distributed File Systems do for servers what a file system does for a hard disk.DFS File ProtocolsNot limited to a single protocolRegardless of client used, can support mapping of:–Servers–Shares–FilesSupports these provided that the client supports the native server and shareHistoryThe UNC (Universal Naming Convention) was required to specify the physical server and share to access file information–i.e. \\Server\share\path\filenameCould be used directly by drive mapping–i.e. X:\path\fileameAs network continues to grow mapping shares individually scales poorlySolution to historical problemsWindows DFS solves these problems by linking physical storage into logical representation.Permits shares to be hierarchally connected to other Windows sharesMake physical location of data transparent to users and applicationsDFS Features and Benefits Feature: Custom hierarchical view of shared network resources –Description: By linking shares together, administrators can create a single hierarchical volume that behaves as though it were one giant hard drive. Individual users can create their own Dfs volumes, which in turn can be incorporated by other Dfs volumes. These are called inter-Dfs links. –Benefit: Provides a simplified view of network shares that can be customized by the administrator.DFS Features and Benefits (Continued) Feature: Flexible volume administration Description: Individual shares participating in the Dfs volume can be taken offline without affecting the remaining portion of the volume name space. Benefit: Allows administrators to manage physical network shares, independent of their logical representation to users.DFS Features and Benefits (Continued) Feature: Graphical administration tool –Description: Each Dfs root is administered with an easy-to-use graphical administration tool that permits browsing, configuration of volumes, alternates, and inter-Dfs links, as well as administration