1、本科毕业论文（设计）外文翻译ALOWBANDWIDTHNETWORKFILESYSTEMATHICHAMUTHITACHAROEN,BENJIECHEN,ANDDAVIDMAZIERESMITLABORATORYFORCOMPUTERSCIENCEANDNYUDEPARTMENTOFCOMPUTERSCIENCEFATHICHA,BENJIEGLCSMITEDU,DMCSNYUEDUABSTRACTUSERSRARELYCONSIDERRUNNINGNETWORKFILESYSTEMSOVERSLOWORWIDEAREANETWORKS,ASTHEPERFORMANCEWOULDBEUNACC
2、EPTABLEANDTHEBANDWIDTHCONSUMPTIONTOOHIGHHOWEVER,EFFICIENTREMOTEFILEACCESSWOULDOFTENBEDESIRABLEOVERSUCHNETWORKSPARTICULARLYWHENHIGHLATENCYMAKESREMOTELOGINSESSIONSUNRESPONSIVERATHERTHANRUNINTERACTIVEPROGRAMSSUCHASEDITORSREMOTELY,USERSCOULDRUNTHEPROGRAMSLOCALLYANDMANIPULATEREMOTEFILESTHROUGHTHEFILESYST
3、EMSOITWOULDREQUIREANETWORKFILESYSTEMTHATCONSUMESLESSBANDWIDTHTHANMOSTCURRENTFILESYSTEMSTHISPAPERPRESENTSLBFS,ANETWORKFILESYSTEMDESIGNEDFORLOWBANDWIDTHNETWORKSLBFSEXPLOITSSIMILARITIESBETWEENFILESANDVERSIONSOFTHESAMEFILETOSAVEBANDWIDTHITAVOIDSSENDINGDATAOVERTHENETWORKWHENTHESAMEDATAHASBEENALREADYFOUND
4、INTHESERVERSFILESYSTEMORTHECLIENTSCACHEUSINGTHISTECHNIQUEINCONJUNCTIONWITHCONVENTIONALCOMPRESSIONANDCACHING,LBFSCONSUMESOVERANORDEROFMAGNITUDELESSBANDWIDTHTHANTRADITIONALNETWORKFILESYSTEMSONCOMMONWORKLOADSKEYWORDSPORTNETWORKFILELBFSFILES1INTRODUCTIONTHISPAPERDESCRIBESLBFS,ANETWORKFILESYSTEMDESIGNEDF
5、ORLOWBANDWIDTHNETWORKSPEOPLETYPICALLYRUNNETWORKFILESYSTEMSOVERLANSORCAMPUSAREANETWORKSWITH10MBIT/SECORMOREBANDWIDTHDATATRANSFERSSATURATEBOTTLENECKLINKSANDCAUSEUNACCEPTABLEDELAYSOVERSLOWER,WIDEAREANETWORKSINTERACTIVEPROGRAMSFREEZE,NOTRESPONDINGTOUSERINPUTDURINGFILEI/O,BATCHCOMMANDSCANTAKEMANYTIMESTHE
6、IRNORMALEXECUTIONTIME,ANDOTHERLESSAGGRESSIVENETWORKAPPLICATIONSFITFORBANDWIDTHUSERSMUSTTHEREFOREEMPLOYDIFFERENTTECHNIQUESTOACCOMPLISHWHATTHEYWOULDDOTHROUGHTHEFILESYSTEMINTHEAREAOFLANPEOPLEOCCASIONALLYWORKOVERNETWORKSSLOWERTHANLANSEVENTHROUGHBROADBANDINTERNETACCESS,APERSONWORKINGATHOMEUSUALLYHASAFRAC
7、TIONOFAMBIT/SECOFUPSTREAMBANDWIDTHACOMPANYWHICHOWNSBRANCHOFFICESANDAGENCIESINSEVERALCITIESMAYHAVEMANYUSERSCOLLABORATINGOVERASINGLE15MBIT/SECT1LINEACONSULTANTCONSTANTLYTRAVELINGBETWEENVARIOUSSITESMAYWANTTOSITDOWNANDACCESSTHESAMEPROJECTFILESFROMEVERYLOCATIONINTHEABSENCEOFANETWORKFILESYSTEM,PEOPLEGENER
8、ALLYRESORTTOONEOFTWOMETHODSOFACCESSINGREMOTEDATATHEYEITHERMAKEOREDITLOCALCOPIESOFFILES,RUNNINGTHERISKOFANUPDATECONFLICTMAYBETHEYUSEREMOTELOGINTOVIEWANDEDITFILESINAPLACEONANOTHERMACHINEIFTHENETWORKHASLONGLATENCY,REMOTELOGINISPARTICULARLYFRUSTRATINGASINTERACTIVEAPPLICATIONSARESLOWINRESPONDINGTOUSERSIN
9、PUTWHATSWORSE,MANYGRAPHICALAPPLICATIONS,SUCHASFIGUREEDITORSANDPOSTSCRIPTPREVIEWERS,CONSUMETOOMUCHBANDWIDTHTORUNPRACTICALLYOVERTHEWIDEAREANETWORKNETWORKFILESYSTEMSHAVETHEPOTENTIALTOALLEVIATETHEINCONVENIENCESASSOCIATEDWITHREMOTEDATAACCESSINADDITIONTOOFFERINGTHEINTERFACEPEOPLEALREADYPREFERLOCALAREANETW
10、ORKSTOAFILESYSTEMWHICHCANPROVIDETIGHTCONSISTENCY,AVOIDINGTHEPROBLEMOFCONFLICTSWHENTWOPEOPLEUPDATETHESAMEFILEFILESYSTEMSCANALSOBETTERTOLERATENETWORKLATENCYTHANREMOTELOGINSESSIONSBYRUNNINGINTERACTIVEPROGRAMSLOCALLYANDACCESSINGREMOTEDATATHROUGHAFILESYSTEM,ONEAVOIDSTHEOVERHEADOFANETWORKROUNDTRIPONEVERYU
11、SERINPUTEVENTTOBEMOREPRACTICALOVERTHEWIDEAREANETWORK,HOWEVER,AFILESYSTEMMUSTCONSUMESIGNIFICANTLYLESSBANDWIDTHTHANMOSTCURRENTFILESYSTEMSITISPOSSIBLETOMAINTAINACCEPTABLEPERFORMANCEANDTOAVOIDMONOPOLIZINGNETWORKLINKSINUSEFOROTHERPURPOSESUNFORTUNATELY,APPLICATIONWRITERSCOMMONLYASSUMETHATFILEI/OWILLBENOSL
12、OWERTHANAMEGABYTEORSOPERSECONDFORINSTANCE,ANINTERACTIVEEDITORWILLSTOPTOWRITEOUT100KBYTE“AUTOSAVE”FILESWITHOUTWORRYINGABOUTDELAYINGAUSERSTYPINGORCONSUMINGSIGNIFICANTRESOURCESATRADITIONALFILESYSTEMTRANSMITSTHEENTIRECONTENTSOFSUCHFILESOVERTHENETWORK,BLOCKINGTHEEDITORFORTHEDURATIONOFTHETRANSFERINCONTRAS
13、T,LBFSOFTENTRANSMITSFARLESSDATATHANTHATAPPLICATIONSWRITE,GREATLYREDUCINGTHETIMEWHICHCOSTWAITINGFORFILEI/OTOREDUCEITSBANDWIDTHREQUIREMENTS,LBFSEXPLOITSCROSSFILESIMILARITIESFILESWRITTENOUTBYAPPLICATIONSOFTENCONTAINANUMBEROFSEGMENTSINCOMMONWITHOTHERFILESORPREVIOUSVERSIONSOFTHESAMEFILEAUTOSAVEFILESAREON
14、LYONEEXAMPLEOBJECTFILESOUTPUTBYCOMPILERS,TEMPORARYFILESUSEDBYTHERCSREVISIONCONTROLSYSTEM,POSTSCRIPTFILES,ANDWORDPROCESSINGDOCUMENTSOFTENCONTAINSUBSTANTIALSIMILARITYFROMONEREVISIONTOTHENEXTANYCOPYINGORCONCATENATIONOFFILES,SUCHASWHENBUILDINGPROGRAMLIBRARIESOUTOFOBJECTFILES,ALSOLEADSTOSIGNIFICANTDUPLIC
15、ATIONOFCONTENTSTOEXPLOITTHESEINTERFILESIMILARITIES,THELBFSFILESERVERDIVIDESTHEFILESITSTORESINTOCHUNKSANDINDEXESTHECHUNKSBYHASHVALUETHELBFSCLIENTSIMILARLYINDEXESALARGEPERSISTENTFILECACHEWHENTRANSFERRINGAFILEBETWEENTHECLIENTANDSERVER,LBFSIDENTIFIESCHUNKSOFDATATHATTHERECIPIENTALREADYHASINOTHERFILESANDA
16、VOIDSTRANSMITTINGTHEREDUNDANTDATAONTHENETWORKINCONJUNCTIONWITHCONVENTIONALCOMPRESSION,THISTECHNIQUESAVESOVERANORDEROFMAGNITUDEOFCOMMUNICATIONSBANDWIDTHONMANYCOMMONWORKLOADSLBFSPROVIDESTRADITIONALFILESYSTEMSEMANTICSANDCONSISTENCYFILESRESIDESAFELYONTHESERVERONCECLOSED,ANDCLIENTSSEETHESERVERSLATESTVERS
17、IONWHENTHEYOPENAFILETHUS,LBFSCANREASONABLYBEUSEDINAPLACEOFANYOTHERNETWORKFILESYSTEMWITHOUTBREAKINGSOFTWAREORDISTURBINGUSERSOTHERFILESYSTEMSHAVEDEALTWITHSLOWANDEVENINTERMITTENTNETWORKCONNECTIVITYBYRELAXINGFILESYSTEMCONSISTENCYTHESETECHNIQUESLARGELYCOMPLEMENTLBFSS,ANDCOULDBECOMBINEDWITHLBFSFOREVENGREA
18、TERBANDWIDTHSAVINGSHOWEVER,ASALTEREDSEMANTICSMAYNOTBESUITABLEFORALLPURPOSES,WECHOSETOFOCUSONREDUCINGBANDWIDTHTOSEEJUSTHOWMUCHWECOULDSAVEWITHOUTCHANGINGACCEPTEDCONSISTENCYGUARANTEESTHENEXTSECTIONDESCRIBESRELATEDWORKINSECTION3ITGIVESLBFSSALGORITHMFORFINDINGCOMMONALITYBETWEENFILESANDEXPLAINSHOWTHELBFSP
19、ROTOCOLTAKESADVANTAGEOFITINSECTION4ITDESCRIBESTHEIMPLEMENTATIONOFLBFSINSECTION5ITSHOWSHOWEFFECTIVELBFSSTECHNIQUEFORCOMPRESSINGFILETRAFFICCANBEFINALLY,INSECTION6ARESULTCONCLUDES2RELATEDWORKPASTPROJECTSHAVEATTACKEDTHEPROBLEMOFNETWORKFILESYSTEMSONSLOWNETWORKSFROMSEVERALANGLESLBFSCOMPLEMENTSMOSTPREVIOUS
20、WORKBECAUSEITPROVIDESCONSISTENCYANDDOESNOTPLACESIGNIFICANTHARDWAREORFILESYSTEMSTRUCTUREREQUIREMENTSONTHESERVER,LBFSSAPPROACHCANUNOBTRUSIVELYBECOMBINEDWITHOTHERTECHNIQUESTOGETADDITIONALSAVINGSINNETWORKBANDWIDTHANUMBEROFFILESYSTEMSHAVEPROPERTIESTHATHELPTHEMTOLERATEHIGHNETWORKLATENCYAFS9USESSERVERCALLB
21、ACKSTOTELLCLIENTSWHENOTHERCLIENTSHAVEMODIFIEDCACHEDFILESTHUS,USERSCANOFTENACCESSCACHEDAFSFILESWITHOUTREQUIRINGANYNETWORKTRAFFICLEASES7AREAMODIFICATIONTOCALLBACKSINWHICHTHESERVERSOBLIGATIONTOINFORMACLIENTOFCHANGESEXPIRESAFTERACERTAINPERIODOFTIMELEASESREDUCETHESTATESTOREDBYASERVER,FREETHESERVERFROMCON
22、TACTINGCLIENTSWHOHAVENTTOUCHEDAFILEINAWHILE,ANDAVOIDPROBLEMSTHATTHESERVERHASPROMISEDACALLBACKHASCRASHEDORGONEOFFTHENETWORKTHENFS4PROTOCOL20REDUCESNETWORKROUNDTRIPSBYBATCHINGFILESYSTEMOPERATIONSALLOFTHEABOVETECHNIQUESAREAPPLICABLETOLBFSINFACT,LBFSCURRENTLYUSESLEASESANDALARGE,PERSISTENTCACHETOPROVIDEA
23、FSLIKECLOSETOOPENCONSISTENCYMANYFILESYSTEMSUSEWRITEBEHINDTOTOLERATELATENCYECHO14PERFORMSWRITEBEHINDOFMETADATAOPERATIONS,ALLOWINGIMMEDIATECOMPLETIONOFOPERATIONSTHATTRADITIONALLYREQUIREANETWORKROUNDTRIPINJETFILE8,THELASTMACHINETOWRITEAFILEBECOMESTHEFILESSERVER,ANDCANTRANSMITITSCONTENTSDIRECTLYTOTHENEX
24、TREADERTHECODAFILESYSTEM10SUPPORTSSLOWNETWORKSANDEVENDISCONNECTEDOPERATIONCHANGESTOTHEFILESYSTEMARELOGGEDONTHECLIENTANDWRITTENBACKTOTHESERVERINTHEBACKGROUNDWHENTHEREISNETWORKCONNECTIVITYTOIMPLEMENTTHISFUNCTIONALITY,CODAPROVIDESWEAKERTHANTRADITIONALCONSISTENCYGUARANTEESITALLOWSUPDATECONFLICTS,WHICHUS
25、ERSMAYNEEDTORESOLVEMANUALLYCODASAVESBANDWIDTHBECAUSEITAVOIDSTRANSFERRINGFILESTOTHESERVERWHENTHEYAREDELETEDOROVERWRITTENQUICKLYONTHECLIENTLBFS,INCONTRAST,SIMPLYREDUCESTHEBANDWIDTHREQUIREDFOREACHFILETRANSFERRINGTHUS,LBFSCOULDBENEFITFROMCODASTYLEDEFERREDOPERATIONS,ANDCODACOULDBENEFITFROMLBFSFILETRANSFE
26、RCOMPRESSIONBAYOU18FURTHERINVESTIGATESCONFLICTRESOLUTIONFOROPTIMISTICUPDATESINDISCONNECTEDSYSTEMSBUTUNLIKECODA,ITDOESNOTPROVIDEAFILESYSTEMRATHER,BAYOUSUPPLIESANAPIWITHWHICHTOIMPLEMENTAPPLICATIONSPECIFICMERGINGANDCONFLICTRESOLUTIONOCEANSTORE2APPLIESBAYOUSCONFLICTRESOLUTIONMECHANISMSTOAFILESYSTEMANDEX
27、TENDSITTOWORKWITHUNTRUSTEDSERVERSWHOONLYEVERSEEDATAINENCRYPTEDFORMATTACT25EXPLORESTHESPECTRUMBETWEENABSOLUTECONSISTENCYANDBAYOUSWEAKERMODELLEEETAL12HAVEEXTENDEDCODATOSUPPORTOPERATIONBASEDUPDATESAPROXYCLIENTSTRONGLYCONNECTEDTOTHESERVERDUPLICATESTHECLIENTSCOMPUTATIONINTHEHOPESOFDUPLICATINGITSOUTPUTFIL
28、ESUSERSRUNAMODIFIEDSHELLTHATBUNDLESUPCOMMANDSFORTHEPROXYCLIENTTOREEXECUTEUSINGFORWARDERRORCORRECTION,THECLIENTANDPROXYCLIENTCANEVENPATCHUPSMALLGLITCHESINTHEOUTPUTFILES,SUCHASDIFFERENTDATES,WHENSUCCESSFUL,OPERATIONBASEDUPDATESDELIVERATREMENDOUSBANDWIDTHSAVINGSHOWEVER,THETECHNIQUEISFAIRLYCOMPLEMENTARY
29、TOLBFSLBFSWORKSWELLWITHINTERACTIVEAPPLICATIONSSUCHASEDITORSTHATITWOULDBEHARDTOREEXECUTEONAPROXYCLIENTOPERATIONBASEDUPDATESCANREDUCECOMMUNICATIONSBANDWIDTHWITHCOMMANDLINEUTILITIESSUCHASIMAGECONVERTERSFORWHICHLBFSOFFERSNOSAVINGSOPERATIONBASEDUPDATESREQUIREADEDICATEDPROXYCLIENTMACHINE,MAKINGTHEMABITCUM
30、BERSOMETOSETUPPERHAPSFORTHISREASONTHETECHNIQUEISNOTINWIDESPREADUSEBYANYFILESYSTEMTODAYSPRINGANDWETHERALLHAVEPROPOSEDAPROTOCOLINDEPENDENTTECHNIQUEFORELIMINATINGREDUNDANTNETWORKTRAFFIC21THEYASSUMETWOCOOPERATINGCACHESATEITHERENDOFASLOWNETWORKLINKBOTHCACHESSTOREIDENTICALCOPIESOFTHELASTNMEGABYTESOFNETWOR
31、KTRAFFICFORVALUESOFNUPTO100WHENONEENDMUSTSENDDATATHATALREADYEXISTSINTHECACHE,ITINSTEADSENDSATOKENSPECIFYINGWHERETOFINDTHEDATAINTHECACHETOIDENTIFYREDUNDANTTRAFFIC,THETWOENDSINDEXCACHEDATABY64BYTEANCHORS13,RANDOMLYCHOSENBASEDONHASHVALUEWHENDATATOBESENTHASA64BYTEANCHORINCOMMONWITHPREVIOUSTRAFFIC,THEMAT
32、CHINGREGIONEXPANDSINBOTHDIRECTIONSTOELIDETHEGREATESTAMOUNTOFDATALBFSSAPPROACHISSIMILARTOTHESPRINGANDWETHERALLTECHNIQUEINSPIRITHOWEVER,LBFSSUPPORTSMULTIPLECLIENTSACCESSINGTHEFILESYSTEMANDEVENLOCALUSERSCHANGINGTHEFILESYSTEMUNDERNEATHTHESERVERTHUS,ITCANNOTASSUMETHATTHECLIENTANDTHESERVERHAVETHESAMESITUA
33、TIONRSYNC23COPIESADIRECTORYTREEOVERTHENETWORKONTOANOTHERDIRECTORYTREECONTAININGSIMILARFILESTYPICALLYFROMAPREVIOUSVERSIONOFTHESAMETREERSYNCSAVESBANDWIDTHBYEXPLOITINGCOMMONALITYBETWEENFILESTHEPROBLEMISSIMILARTOSYNCHRONIZINGACLIENTSFILECACHEWITHTHESERVERORVICEVERSAINFACT,TRIDGELLPROPOSEASUGGESTIONTHATP
34、EOPLECANAPPLYRSYNCTOAFILESYSTEMINHISTHESISTHOUGHRSYNCWASONEOFTHEINSPIRATIONSFORLBFS,FILECACHINGINREALTIMEISSOMEWHATDIFFERENTFROMDIRECTORYTREEMIRRORINGLBFSTHUSUSESADIFFERENTMETHODWEDISCUSSTHERSYNCALGORITHMINMOREDETAILANDCOMPAREITTOOURAPPROACHINSECTION31ANUMBEROFUNIXUTILITIESOPERATEONDIFFERENTIALFILED
35、IFFCOMPUTESTHEDIFFERENCEBETWEENTWOTEXTFILESPATCHAPPLIESTHEOUTPUTOFDIFFTOTRANSFORMONEFILEINTOTHEOTHERTHEREHAVEBEENSTUDIESOFTHEPROBLEMOFDESCRIBINGONEFILEINTERMSOFAMINIMALSETOFEDITSTOANOTHER22MOGULETAL17HASINVESTIGATEDTRANSMITTINGSUCHDELTASTOSAVEBANDWIDTHWHENUPDATINGCACHEDWEBPAGESTHECVS1VERSIONMANAGEME
36、NTSYSTEMSHIPSPATCHESOVERTHENETWORKTOBRINGAUSERSWORKINGCOPYOFADIRECTORYTREEUPTODATEUNLIKECVS,HOWEVER,AFILESYSTEMCANNOTSTOREACOMPLETEREVISIONHISTORYFORALLFILESTHEREFORE,THELBFSSERVERWILLTYPICALLYNOTHAVEANEXACTOLDVERSIONFROMWHICHTOCOMPUTEDIFFERENCES端口上的网络文件系统ATHICHAMUTHITACHAROEN陈,大卫,BENJIE清人著述的眼睛麻省理工学
37、院的实验室,计算机科学和纽约大学计算机科学部门FATHICHA,BENJIEGLCSMITEDUDMCSNYUEDU。摘要用户很少考虑网络文件系统运行缓慢,和广域网的性能将是不可接受的,网络带宽消耗太高了。尽管如此,有效的远程文件访问经常会在理想NETWORKSPARTICULARLY当高的延迟使得远程登录会话生气。而不是自己开公司等交互程序,用户可以运行的远程编辑程序局部和操纵远程文件通过文件系统。这样做,然而,要消费的网络文件系统比大多数带宽较当前文件系统。提出了一种网络LBFS端口上的文件系统设计的网络。利用相似之处LBFS文件或版本的相同的文件节省带宽。它避免了通过网络发送数据时相同的
38、数据已建立在这个伺服器文件系统或客人的高速缓冲存储。使用这个技术,结合传统的压缩和缓冲、LBFS消耗在一份带宽较级比传统的网络文件系统在共同的工作量。关键词端口网络文件LBFS文件1前言这篇文章介绍了一种网络LBFS端口上的文件系统设计的网络。人们总跑的网络文件系统CAMPUSAREA网络在LAN或10MBIT/秒或更大的带宽。在较慢,饱和、数据传输大面积网络链接和原因瓶颈无法接受的延迟。交互程序冻结,不理在用户的输入文件I/O、批量命令多次CANTAKE正常执行时间和其他侵袭性较小带宽很喜欢网络应用程序。用户必须因此雇用很多不同的方法来做到在局域网,他们会做通过文件系统。人们经常有机会工作网
39、络慢于局域网。即使有宽带上网,一个人在家工作通常只有一小段MBIT/秒的上游带宽。公司在多个城市设有分公司和办事处,可能有很多用户协作的单一15MBIT/秒T1专线。不断的一名顾问,不同的地点可以旅行想坐下来谈,存取同一个项目文件的位置。在那些没有,人们通常的网络文件系统的两种方法手段访问远程数据。他们既可以让和编辑当地拷贝文件、运行的风险更新冲突,否则,他们使用远程登录查看和编辑的文件在适当的位置在另一个机器。如果网络一直延迟、远程登陆特别令人沮丧的是交互式应用缓慢在应对用户输入的信息。更糟的是,许多图形应用程序,比如花样编辑和其它PREVIEWERS,消耗过多的带宽统率超过广域网络。网络文
40、件系统有可能减少不便远程数据相关的访问。除了提供接口人已经更有利于LOCALAREA网络文件系统能够提供紧一致性,避免冲突的问题当两个人更新一样的文件。文件系统也会更好。2相关研究过去的作品着手解决的网络文件系统网络速度从多个角度。过去大多数LBFS补充工作。因为它提供一致性和不要放置重大的硬件或文件系统结构要求的方式的服务器,LBFS做好其他技术相结合,以索取额外需要的储蓄在网络带宽。大量的文件系统有属性能帮助他们忍受高网络的延迟。AFS9使用服务器回调通知客户在其他客户有修改缓冲文件。因此,用户可以经常访问缓存AFS文件无需任何交通网络。租赁7中是一个修改回调,服务器的义务向客户的变化某一
41、段时间。租赁减少国家储存于服务器,免费的服务器接触客户文件上也没碰过一段时间,避免问题当客户服务器已经承诺一个回调有撞毁或坏了网络。NFS4的协议20减少网络圆游配料文件系统操作。所有上述技术适用于LBFS。事实上,LBFS目前采用租赁和一个大的永久缓存提供AFSLIKECLOSETOOPEN一致性。许多文件系统使用WRITEBEHIND宽容的延迟。回声14执行WRITEBEHIND元数据操作的,允许的操作,立即完成传统上需要一个网络往返。在JETFILE8,最后写一个文件会自动机器,文件的服务器,能可靠的传送它的内容直接到下一个读者。高精密度的文件系统10所聚集的相当慢网络,甚至支持断开的操
42、作。文件系统的变化都记录在客户端和书面返回给服务器在背景时,有网络连接。来实现这个功能,柯达提供WEAKERTHANTRADITIONAL一致性保证。它允许更新时发生冲突,哪些用户可能需要解决手动操作。柯达节省带宽,因为它避免了文件传输到服务器当他们会被删除或覆盖上快速的客户。相比之下,LBFS简单所需要的带宽减少每个文件转移。因此,LBFS可以受益CODASTYLE递延操作,和结尾能受益于LBFS文件传输压缩。河口18进一步调查冲突解决那些乐观的更新,在断开,系统,但与柯达,不提供文件系统。相反,河口提供了一个API来执行特定应用的融合和解决冲突。OCEANSTORE2的河口适用于冲突机制来
43、一个文件系统和延长它使用不可信赖的服务器,只看到以往用加密的数据格式。机智25探讨了谱的一致性和河口的绝对之间较弱的模型。李ET铝12。OPERATIONBASED已经扩展相对于支持更新。一个PROXYCLIENT强连通到服务器复制客户的计算,希望复制其输出文件。用户运行一种改进的外壳,捆起来,PROXYCLIENTREEXECUTE的命令。应用前景的客户端和纠错、PROXYCLIENT甚至可以修补小毛病输出文件,例如各种日期。成功匹配时,提供巨大的带宽OPERATIONBASED更新存款。然而,这项技术是LBFS相当相辅相成的。LBFS运作良好,与在TERACTIVE应用,如编辑们表示,很难
44、将在PROXYCLIENTREEXECUTE。OPERATIONBASED更新可降低通讯带宽与命令行工具如图像变换器LBFS没有提供的积蓄。OPERATIONBASED更新需要一个专用PROXYCLIENT机、使他们有点麻烦。也许因为这个缘故技术不广泛应用任何文件系统今天。SPRING和WETHERALL已经提出一PROTOCOLINDEPENDENT技术来消除多余的网络流量21。他们承担的两种合作两端缓存对慢网络连接。两个相同拷贝缓存的最后N兆的网络流量N价值100。当一个端头应发送数据在隐藏所中业已存在,它只能发送一个令牌指定在哪里可以找到这些数据在高速缓存中。识别多余的交通、两端64BY
45、TE缓存数据指标锚13,基于随机挑选的哈希值。当数据派有64BYTE锚定的共同点与以前的交通匹配的地区,在两个方向上扩大了ELIDE极大的数据。类似的方法是LBFS春天和精神上的WETHERALL技术。然而,LBFS支持多个客户的存取档案文件系统,甚至本地用户改变下面的文件系统服务器。因此,它就不能假定客户端和服务器拥有完全相同的状态。复制一个23RSYNC目录树在另一网络包含相似的FILESTYPICALLY目录树从先前的版本同样的树上。RSYNC节省带宽之间利用共性文件。问题是类似于同步客户的文件缓存和服务器或反之亦然。事实上,TRIDGELL提出应用RSYNC到一个文件系统在毕业论文。虽然RSYNC是LBFS启示,文件缓存实时目录树有些不一样镜像。LBFS因此使用一种不同的算法。我们讨论的RSYNC算法在更多的细节,并把它比作我们的方法在31节。一些UNIX公用事业使用差异文件。差异计算FILES两个文本的区别的输出补丁适用差异将一个文件。这里有一个研究这个问题的描述一个文件按照最少编辑到另一个22。巨头ET17人进行了调查,传播该项目增量更新时节省频宽缓存网页。CVS1版本管理系统补丁船只在网络上用户工作带一份最新的目录树。不像CVS,然而,一个文件系统不能存储一个完整的版本历史所有文件。因此,LBFS服务器通常没有一个确切的老版本来计算差异。
