Network File SystemsNFS GeneralNetwork File System (NFS)DistributionDistributionSlide 6TransparencyTransparencyPerformanceSlide 10Slide 11Concurrent file updatesSlide 13Slide 14Sample Network File SystemsSlide 16NFS ProtocolNetwork File System ProtocolVersions and variationsSlide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27PlatformsSlide 29Slide 30Typical implementationSlide 32Protocol development versus Competing protocolsProtocol development versus competing protocolsSlide 35PresentSlide 37Slide 38AFSAndrew File System (AFS)FeaturesSlide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48ImplementationsSlide 50Available permissionsSlide 52Slide 53Slide 54SMBServer Message Block (SMB)Slide 57HistorySlide 59Slide 60Slide 61Slide 62Slide 63ImplementationSlide 65Slide 66Slide 67Slide 68Slide 69Slide 70Slide 71Slide 72Versions and implementationsSlide 74Slide 75Slide 76Network File SystemsNFSAFSSMBNFS Generalhttp://en.wikipedia.org/wiki/Network_file_systemNetwork File System(NFS)Any computer file system that supports sharing of files and other resources as persistent storage over a computer network First file servers were developed in the 1970s, In 1985 Sun Microsystems created the Network File System (NFS)Became the first widely used distributed file systemOther notable distributed file systemsAndrew File System (AFS)Server Message Block SMBAKA CIFSDistributionDistributionDistributed File System (DFS)Network file system with: Clients, servers, and storage devicesSpread throughout the machines of a distributed system or intranetService activity occurs across the networkSystem has multiple and independent storage devicesSome DFS servers run on dedicated machinesOthers a machine can be both a server and a clientA DFS can be implemented:As part of a distributed operating systemBy a software layer Managing the communication between conventional operating systems and file systemsDistributionDistinctive feature of a DFS:System with many and autonomous clients and serversTransparencyTransparencyA DFS should appear to its users to be a conventional, centralized file systemMultiplicity and dispersion of its servers and storage devices should be invisible Client interface used by programs should not distinguish between local and remote filesThe DFS locates the files and arranges the transport of dataPerformancePerformanceMost important performance measurement of a DFS:Amount of time needed to satisfy service requestsTypical performance constraints:Conventional systems:Disk-access timeSmall amount of CPU-processing timeDFS:Additional overhead due to the distributed structureIncludes:Time to deliver the request to a serverTime to deliver the response to the clientFor each direction, a CPU overhead of running the communication protocol softwarePerformanceThe performance of a DFS can be viewed as one dimension of its transparencyIdeally, it would be comparable to that of a conventional file systemConcurrent file updatesConcurrent file updatesA DFS should allow multiple client processes on multiple machines to access and update the same filesUpdates to the file from one client should not interfere with access and updates from other clientsConcurrency control or locking may be:Built into the file systemProvided by an add-on protocolNetwork File SystemsSample Network File SystemsClient-server file systems9P Amazon S3 Coda Secure File System (SFS) Self-certifying File System (SFS)Sample Network File SystemsDistributed file systemsCeph Andrew File System (AFS), OpenAFS DCE Distributed File SystemRemote file access protocol used with the Distributed Computing EnvironmentGoogle File SystemFile system that is optimized for Google's core storage needsHadoopJava software framework that supports distributed applications running on large clusters of commodity computersKosmos FSHigh performance distributed file system. It is also integrated with hadoop. LustreDistributed file system for large scale cluster computingMicrosoft Distributed File SystemSet of client and server services for organizing many distributed SMB file shares into a distributed file systemGlusterFSPlatform for developing clustering applicationsParallel Virtual File SystemParallel file system that focuses on high performance access to large data setsNFS Protocolhttp://en.wikipedia.org/wiki/Network_File_System_%28protocol%29Network File System ProtocolNetwork file system protocol:Allows a user on a client computer to access files over a network As if the network devices were attached to its local disksOriginally developed by Sun Microsystems in 1984NFS builds on the Open Network Computing Remote Procedure Call (ONC RPC) systemThe Network File System protocol is specified inRFC 1094, RFC 1813, and RFC 3530 (which obsoletes RFC 3010)Versions and variationsVersions and variationsVersion 1Sun used only for in-house experimental purposesDid not release it to the publicVersions and variationsVersion 2 of the protocolOriginally operated entirely over UDPDefined in RFC 1094March 1989Designers meant to keep the protocol statelessLocking (for example) implemented outside of the core protocolVersions and variationsVersion 3 (RFC 1813, June 1995) added:Support for 64-bit file sizes and offsetsHandle files larger than 4 gigabytes (GB) Support for asynchronous writes on the serverImprove write performanceAdditional file attributes in many repliesAvoid the need to re-fetch themREADDIRPLUS operationGet file handles and attributes along with file names when scanning a directoryAssorted other improvementsVersions and variationsAt the introduction of Version 3Vendor support for TCP as a transport-layer protocol began increasingSeveral vendors had already added support for NFS Version 2 with TCP as a transportSun Microsystems added support for TCP as a transport for NFS at the same time it added support for Version 3Using TCP as a transport made using NFS over a WAN more feasibleVersions and variationsVersion 4 became the first version developed with the IETFAfter Sun Microsystems handed over the development of the NFS protocolsVersions and variationsVersion 4 includes:Performance improvementsMandates strong security Introduces a