Linux操作系统01-简介.ppt

AcegeneITCo.Ltd.,1,Linux操作系统简介,周炯上海艾基信息技术有限公司,AcegeneITCo.Ltd.,2,内容提要,Linux简介Linux的安装SHELL及常用程序文件编辑器vi目录和文件管理文件系统管理用户管理,网络管理网络文件系统模块安装和配置系统管理系统优化开发工具Internet管理,AcegeneITCo.Ltd.,3,Linux简介,Linux操作系统是可以运行在许多不同类型的计算机上的一种操作系统的“内核”。它是提供命令行或者程序与计算机硬件之间接口的软件的核心部分。Linux操作系统内核管理以下事情：比如内存、采用什么方法以及在什么时候打开或者关闭文件、哪一个进程或者程序可以获得计算机的中央处理单元(CPU)等等。Linux操作系统可以说是UNIX操作系统的一个克隆体，它最初是在1991年10月5日由它的作者LinusTorvalds于赫尔辛基大学发布的。,AcegeneITCo.Ltd.,4,Linux功能,所有主要的网络协议硬盘配额支持全部的源代码国际化的字体和键盘作业控制数学协处理器仿真内存保护多平台,多处理器多用户多任务共享的库文件支持多种文件系统虚拟控制台虚拟内存其他更多功能,AcegeneITCo.Ltd.,5,GPL和Free,Linux操作系统遵从GNU公共许可证（GNUPublicLicense，简称GPL）的规定。Linux对外的一个重要的特点就是”Free”，自由和免费。,AcegeneITCo.Ltd.,6,WhatisLinux?,Linuxisanoperatingsystemwiththefollowingattributes:Multi-userMulti-taskingVirtualmemorysystemX-WindowsCompatiblewiththeIEEEPOSIX.1standardNon-proprietarysourcecodeSourcecodeisavailable,AcegeneITCo.Ltd.,7,IsLinuxthesameasUNIX?,ThecommandsetissimilarTheyworkthesameTheylookthesameLinuxcannotusetheUNIXtrademarkLinuxisessentiallyUNIX,AcegeneITCo.Ltd.,8,IsLinuxarealOS?,Yes,absolutelyLinuxisusedInmissioncriticalapplicationsAroundtheworldTherearemanyflavorsofLinuxavailableWecallthem:Distributions,AcegeneITCo.Ltd.,9,Linux发行版本的概念,大多数的Linux操作系统的发行版本都使用标准的Linux内核，但有时候也会稍微加以修改，这个操作系统现在的规模已经变得相当庞大了，因此许多人更愿意购买一张它的CD-ROM光盘。每一种发行版本彼此之间都稍微有一些差异，这些差异主要表现在它们各自的安装程序包上，还表现在安全性与可用性等方面侧重点的不同。把系统内核、附带的工具程序及应用软件包等等打包在一起，这样组成的一个Linux操作系统的集合体就是我们说的某一种发行版本。,AcegeneITCo.Ltd.,10,谁使用Linux操作系统,Linux正在逐渐赢得普通用户的青睐。但是它仍然不是一个适用于普通大众的操作系统。对那些习惯了当今鼠标界面操作系统的人们来说，学习仍是很困难的。需要学习一大套从未接触过的命令，还需要学习与长期形成的概念不相同的那些对待与处理事情的方法。对那些具有UNIX操作系统使用经验的人们来说，Linux可是容易多了。专业用户、系统管理员和计算机开发人员通常都会比一般的用户更容易掌握Linux操作系统。但就是对这些人来说，这方面的学习与实践也需要有足够的耐心与专心。,AcegeneITCo.Ltd.,11,Enterprisevs.Retail,RetaildistributionsFasterreleasecycles(4-6months)Gearedforhome/productivityusersShortersupportlifetimesExamples:RHL9,SuSELinux9EnterpriseleveldistributionsSlowerreleasecycles(12-18months)Longersupportlifetimes(3-5years)Examples:RHEL3/4,SLES9Addsperformanceandscalabilityenhancements,LinuxDistributionOverview,ThecorepartsofaLinuxsystemare:LinuxkernelUserspaceutilitiesandapplicationsThekernelanduserspaceprogramstogethermakeupthecompleteoperatingsystem,LinuxKernel,CorecomponentoftheoperatingsystemConfigurableandtunableProvidesmainOSfunctionsI/O,disk,network,etc.CPUSchedulingMemorymanagementuname-rshowsthekernelversionnumber:,#uname-r2.4.9-e.25,AcegeneITCo.Ltd.,14,Kernelconcepts,Linuxisbasedonamodularnon-microkernelarchitectureAlldevicedriverssharethesamememorywiththekernelDevicedriversaremodularandcanbeloaded/unloadeddynamicallyLinuxismulti-taskingLinuxisavirtual-memoryOSMostkernelparameterscanbemodifiedonthefly,AllcomponentsoftheoperatingsystemaredeliveredviaRPMpackagesKernelSystemutilitiesApplicationsBothRedHatandSLES8distributionsusetheRPMPackageManager(RPM)Originallynamed“RedHatPackageManager”,SoftwarePackages,LinuxUpdates,Applytherecommendedupdatesbythedistributionvendor:MostvendorsprovideautomaticupdatesRedHatNetworksuppliesupdatesautomaticallyup2dateSuSEusesYaST2(YetAnotherSetupTool2)you(YaSTOnlineUpdate),LinuxEnterpriseFeatures,Linuxenterprisefeaturessupport:PerformanceScalabilityReliability,AcegeneITCo.Ltd.,18,SymmetricMultiprocessing,Fullymultiprocessorcapable(SMP)RHEL3:16processorsSLES8:32processorsUniprocessorconfigurationsupportedonbothIntelHyperthreading(HT)enabledonIA-32Physical-to-logicalCPUaffinityscheduling,AcegeneITCo.Ltd.,19,ImprovedMemoryUtilization,Usemorethan4GBofRAMonIA-32RHEL2.1:max16GBsupportedRHEL3:max64GBsupportedSLES8:upto64GBsupportedSomeolderdriversnotcapableofaccessingmorethan4GBofRAMMayperform“bouncebuffering”tocompensateUsuallynotaconcernforenterprise-classdriversKernelmemoryusedmoreefficientlythanbeforeRunmoreprocesseswithoutswapping,AcegeneITCo.Ltd.,20,VirtualMemory,EachprocesshasaprivateaddressspaceKeepsprivatedatainmemorysecurePreventsinter-processdatacorruptionContiguousviewofmemoryDemand-basedpagingPagesare“swapped”outwhenlowonRAMPagesare“swapped”inwhenaccessedagainAllowsthesystemtousemorememorythananysinglespacecanaddress,VirtualFilesystem(VFS),LinuxsupportsmultiplefilesystemsOSisfilesystemindependentMultiplefilesystemscanbeusedsimultaneouslyCross-platformcompatibilityPerformanceVFSprovidesasinglefilesysteminterface,AcegeneITCo.Ltd.,22,Filesystems,Importantonestoknow:ext2/3-RedHatdefault(ext3)reiserfs-SLES8defaultNFS-NetworkFilesystemProcfs-kernelvirtualfilesystemISO9660(CD-ROM)OCFS-OracleClusterFilesystemext2/3andreiserfsarethemostcommonUseOCFSinsteadofrawdevicesinRAC,AcegeneITCo.Ltd.,23,FilesystemCache,BuffersallfilesystemI/OAllfilesystemI/Oiscopiedto/fromcachebuffersBydefault,writesarenotimmediatelyflushedHardwareI/OisdeferredReadsbenefitfrompreviousaccessesaswellasautomaticread-aheadMaynotneedtoperformarealhardwareI/OMadeupofpagecacheandbuffercachePagecachetendstobemoreheavilyusedReducedautomaticallywhenlowonRAM,AcegeneITCo.Ltd.,24,Process,Diskfile,Write,Read,RawDevices,HavetraditionallybeenconsideredthehighperformancesolutionBypassesthefilesystembuffercacheMoveslargerbuffersthanfilesystemI/OsRequiresmoreexperiencedadministration,AcegeneITCo.Ltd.,25,ModularDrivers,Loadablekernelmodules(LKM)Canbeunloaded/reloadedwithoutrebootingModulesprovide:DevicedriversFilesystemdriversSystemcallsNetworkdriversExecutableinterpretersTerminaldevice(TTY)drivers,I/OModes,DiskI/OcanbeperformedinseveraldifferentmodesAsynchronousvs.synchronousDirectvs.buffered,AcegeneITCo.Ltd.,27,StorageInfrastructure,Direct-attachedstorage(DAS)IDE,SCSIe.g.,LSIMegaraidNetwork-AttachedStorage(NAS)NFSe.g.,NetworkApplianceFilerStorageAreaNetworks(SAN)FibreChannele.g.,EMCClariion,AcegeneITCo.Ltd.,28,LinuxClusters,ScalableSharedStorageSCSI,SAN(FibreChannel),Firewire(devel.)MustuserawdevicesorOCFSNetworkAttachedStorage(NFS)LVMandsoftwareRAID(“md”)notcluster-awareLinuxincludesclustermanagementsoftware,AcegeneITCo.Ltd.,29,LinuxKernelEnhancements,PerformanceAsynchronousI/OEliminatekernellocksLargeSGA:4GBSupportmoreOracleusersStabilityGracefuldegradationunderloadManageability(Remote)CrashDumpFac