计算机网络专业英语 课件 L6-2 Text 2 The Details of Network Storage

L6-2

Lesson6NetworkStorageandCloudComputingText2TheDetailsofNetworkStorage要点KeyPoints：专业术语DAS、NAS位置无关的网盘Enhance、improve、drop、reduceRun、carryout、performCompute、computer、computation、computationalAclusteredfilesystemisafilesystemwhichissharedbybeingsimultaneouslymountedonmultipleservers.Thereareseveralapproachestoclustering,mostofwhichdonotemployaclusteredfilesystem(onlydirectattachedstorageforeachnode).Clusteredfilesystemscanprovidefeatureslikelocation-independentaddressing位置无关的寻址

andredundancywhichimprove

reliabilityorreducethecomplexityoftheotherpartsofthecluster.Parallelfilesystemsareatypeofclusteredfilesystemthatspreaddataacrossmultiplestoragenodes,usuallyforredundancyorperformance.mount（加载）指被操作系统识别，可被用户访问。simultaneous同时的synchronous同步的asynchronous异步的“同步”指在通信中使用共同的时钟approach在这里翻译成“方法”,同way、method和means等，approach起源于ap去+proach接近。Afilehostingservice,cloudstorageservice,onlinefilestorageprovider,orcyberlockerisanInternethostingservicespecificallydesignedtohostuserfiles.Itallowsuserstouploadfilesthatcouldthenbeaccessedovertheinternetfromadifferentcomputer,tablet,smartphoneorothernetworkeddevice,bythesameuserorpossiblybyotherusers,afterapasswordorotherauthenticationisprovided.Typically,theservicesallowHTTPaccess,andsometimesFTPaccess.Relatedservicesarecontent-displayinghostingservices(i.e.videoandimage),virtualstorage,andremotebackup.Incomputing,afileserver(orfileserver)isacomputerattachedtoanetworkthathastheprimarypurposeofprovidingalocationforshareddiskaccess,i.e.sharedstorageofcomputerfiles(suchasdocuments,soundfiles,photographs,movies,images,databases,etc.)thatcanbeaccessedbytheworkstationsthatareattachedtothesamecomputernetwork.Thetermserverhighlightstheroleofthemachineintheclient–serverscheme,wheretheclientsaretheworkstationsusingthestorage.Afileserverisnotintendedtoperform

computationaltasks,anddoesnotrunprogramsonbehalfofitsclients.Itisdesignedprimarilytoenablethestorageandretrievalofdatawhilethecomputationiscarriedoutbytheworkstations.workstation是使用服务器（server）提供服务（service）的计算机，即客户机（client）。workstation也指大（中、小）型机的终端，也指性能很好的个人计算机，例如图形工作站（graphicworkstation）scheme组合、体制，client–serverscheme翻译为“客户机—服务器架构”或“c/s架构”。Fileserversarecommonlyfoundinschoolsandoffices,whereusersuseaLANtoconnecttheirclientcomputers.Network-AttachedStorage(NAS)isafile-levelcomputerdatastorageserverconnectedtoacomputernetworkprovidingdataaccesstoaheterogeneousgroupofclients.NASisspecializedforservingfileseitherbyitshardware,software,orconfiguration.Itisoftenmanufacturedasacomputerappliance–apurpose-builtspecializedcomputer.NASsystemsarenetworkedapplianceswhichcontainoneormorestoragedrives,oftenarrangedintological,redundantstoragecontainersorRAID.Thekeydifferencebetweendirect-attachedstorage(DAS)andNASisthatDASissimplyanextensiontoanexistingserverandisnotnecessarilynetworked.NASisdesignedasaneasyandself-containedsolutionforsharingfilesoverthenetwork.BothDASandNAScanpotentiallyincreaseavailabilityofdatabyusingRAIDorclustering.NASprovidesbothstorageandafilesystem.ThisisoftencontrastedwithSAN(StorageAreaNetwork),whichprovidesonlyblock-basedstorageandleavesfilesystemconcernsonthe“client”side.SANprotocolsincludeFibreChannel,iSCSI,ATAoverEthernet(AoE)andHyperSCSI.builtforaspecificpurpose可以简单地表达为purpose-builtfile-level文件级别，block-level（块级别）或block-based，都是指数据的抽象程度（levelofabstraction），上层应用（upperapplication）能使用（employ）的数据结构（datastructure）SANisanetworkwhichprovidesaccesstoconsolidated,blockleveldatastorage.SANsareprimarilyusedtoenhancestoragedevices,suchasdiskarrays,tapelibraries,andopticaljukeboxes,accessibletoserverssothatthedevicesappeartotheoperatingsystemaslocallyattacheddevices.ASANtypicallyhasitsownnetworkofstoragedevicesthataregenerallynotaccessiblethroughthelocalareanetwork(LAN)byotherdevices.ThecostandcomplexityofSANsdroppedintheearly2000stolevelsallowingwideradoptionacrossbothenterprise