【正文】 一時間內(nèi)只有一臺服務(wù)器運(yùn)行。當(dāng)其中運(yùn)行著的一臺服務(wù)器出現(xiàn)故障無法啟動時，另一臺備份服務(wù)器會迅速的自動啟動并運(yùn)行（一般為2分鐘左右），從而保證整個網(wǎng)絡(luò)系統(tǒng)的正常運(yùn)行！雙機(jī)熱備的工作機(jī)制實(shí)際上是為整個網(wǎng)絡(luò)系統(tǒng)的中心服務(wù)器提供了一種故障自動恢復(fù)能力。2．IP負(fù)載調(diào)度均衡技術(shù)用戶通過虛擬IP地址（Virtual IP Address）訪問服務(wù)時，訪問請求的報文會到達(dá)負(fù)載調(diào)度器，由它進(jìn)行負(fù)載均衡調(diào)度，從一組真實(shí)服務(wù)器選出一個，將報文的目標(biāo)地址Virtual IP Address改寫成選定服務(wù)器的地址，報文的目標(biāo)端口改寫成選定服務(wù)器的相應(yīng)端口，最后將報文發(fā)送給選定的服務(wù)器。真實(shí)服務(wù)器的回應(yīng)報文經(jīng)過負(fù)載調(diào)度器時，將報文的源地址和源端口改為Virtual IP Address和相應(yīng)的端口，再把報文發(fā)給用戶。3． 共享存儲共享存儲為服務(wù)器組提供統(tǒng)一的存儲空間，這使得系統(tǒng)的維護(hù)工作比較輕松，如Webmaster只需要更新共享存儲中的頁面，對所有的服務(wù)器都有效。分布式文件系統(tǒng)提供良好的伸縮性和可用性，當(dāng)分布式文件系統(tǒng)的存儲空間增加時，所有服務(wù)器的存儲空間也隨之增大。對于大多數(shù)Internet服務(wù)來說，它們都是讀密集型（Readintensive）的應(yīng)用，分布式文件系統(tǒng)在每臺服務(wù)器使用本地硬盤作Cache（如2Gbytes的空間），可以使得訪問分布式文件系統(tǒng)本地的速度接近于訪問本地硬盤。4．VMware WorkstationVMware Workstation是一款功能強(qiáng)大的桌面虛擬計算機(jī)軟件，提供用戶可在單一的桌面上同時運(yùn)行不同的操作系統(tǒng)，和進(jìn)行開發(fā)、測試 、部署新的應(yīng)用程序的最佳解決方案。VMware Workstation 可在一部實(shí)體機(jī)器上模擬完整的網(wǎng)絡(luò)環(huán)境，以及可便于攜帶的虛擬機(jī)器，其更好的靈活性與先進(jìn)的技術(shù)勝過了市面上其他的虛擬計算機(jī)軟件。對于企業(yè)的 IT 開發(fā)人員和系統(tǒng)管理員而言，VMware 在虛擬網(wǎng)路，實(shí)時快照，拖曳共享文件夾，支持 PXE 等方面的特點(diǎn)使它成為必不可少的工具。六、進(jìn)度安排已完成的工作安排：第1周 確定畢業(yè)設(shè)計題目。下達(dá)任務(wù)書。第2周 根據(jù)任務(wù)書查閱、收集有關(guān)文獻(xiàn)資料。第3～4周 進(jìn)行系統(tǒng)需求分析和方案論證，撰寫并上交開題報告。待完成的工作安排：第5～6周 網(wǎng)絡(luò)模擬環(huán)境的搭建及系統(tǒng)的總體設(shè)計。第7～8周 高可用性集群，LVS均衡負(fù)載集群，共享存儲的詳細(xì)設(shè)計。第9～11周 進(jìn)行相關(guān)配置腳本的編寫及集群系統(tǒng)的實(shí)現(xiàn)。第12～13周 在以上基礎(chǔ)上細(xì)化、完善有關(guān)設(shè)計，并在計算機(jī)上實(shí)現(xiàn)，寫出畢業(yè)設(shè)計（論文）初稿。第14～15周 系統(tǒng)驗(yàn)收；對畢業(yè)論文進(jìn)行修改并定稿；準(zhǔn)備論文答辯。七、閱讀的主要文獻(xiàn)、資料[1] 鳥哥 鳥哥的Linux私房菜基礎(chǔ)學(xué)習(xí)篇(第2版)[M]..[2] :服務(wù)器架設(shè)篇(第2版)[M]..[3] (美) (第5版)[M]..[4] 、服務(wù)器搭建、系統(tǒng)管理、性能調(diào)優(yōu)、集群應(yīng)用[M]..[5]（美)(Karl Kopper).Linux企業(yè)集群:用商用硬件和免費(fèi)軟件構(gòu)建高可用集群[M]..[6] .[J].[7] [J]..[8] [J]..[9] [J].四川理工學(xué)院報(自然科學(xué)版)..[10] [J]..[11] (專業(yè)版)[J]..[12] [M]..[13] [D]..[14] [D]..[15] [J]..[16] LVS中文站點(diǎn)[OL] 附專業(yè)譯文摘自：《Linux企業(yè)集群》(The Linux Enterprise Cluster)英文原文: The Linux Enterprise ClusterOverviewThis chapter will introduce the cluster loadbalancing software called IP Virtual Server (IPVS). The IPVS software is a collection of kernel patches that were merged into the stock version of the Linux kernel starting with version . When bined with the kernel39。s routing and packetfiltering capabilities (discussed in Chapter 2) the IPVSenabled kernel lets you turn any puter running Linux into a cluster load balancer. Together, the IPVSenabled cluster load balancer and the cluster nodes are called a Linux Virtual Server (LVS).The LVS cluster load balancer accepts all ining client puter requests for services and decides which cluster node should reply to each request. The load balancer is sometimes called an LVS Director or simply a Director. In this book the terms LVS Director, Director, and load balancer all refer to the same thing.The nodes inside an LVS cluster are called real servers, and the puters that connect to the cluster to request its services are called client puters. The client puters, the Director, and the real servers municate with each other using IP addresses the same way puters have always exchanged packets over a network。 however, to make it easier to discuss this network munication, the LVS munity has developed a naming convention to describe each type of IP address based on its role in the network conversation. So before we consider the different types of LVS clusters and the choices you have for distributing your workload across the cluster nodes (called scheduling methods), let39。s look at this naming convention and see how it helps describe the LVS cluster.LVS IP Address Name ConventionsIn an LVS cluster, we cannot refer to network addresses as simply IP addresses. Instead, we must distinguish between different types of IP addresses based on the roles of the nodes inside the cluster. Here are four basic types of IP addresses used in a cluster:Virtual IP (VIP) addressThe IP address the Director uses to offer services to client putersReal IP (RIP) addressThe IP address used on the cluster nodesDirector39。s IP (DIP) addressThe IP address the Director uses to connect to the D/RIP networkClient puter39。s IP (CIP) addressThe IP address assigned to a client puter that it uses as a source IP address for requests sent to the clusterThe Virtual IP (VIP)The IP address that client puters use to connect to the services offered by the cluster are called virtual IP addresses (VIPs). VIPs are IP aliases or secondary IP addresses on the NIC that connects the Director to the normal, public network.[1] The LVS VIP is important because it is the address that client puters will use when they connect to the cluster. Client puters send packets from their IP address to the VIP address to access cluster services. You tell the client puters the VIP address using a naming service (such as DNS, DDNS, WINS, LDAP, or NIS), and this is the only name or address that client puters ever need to know in order to use the services inside the cluster. (The remaining IP addresses inside the cluster are not known to the client puter.)A single Director can have multiple VIPs offering different services to client puters, and the VIPs can be public IP addresses that can be routed on the Internet, though this is not required. What is required, however, is that the client puters be able to access the VIP or VIPs of the cluster. (As we39。ll see later, an LVSNAT cluster can use a private intranet IP address for the nodes inside the cluster, even though the VIP on the Director is a public Internet IP address.)The Real IP (RIP)In LVS terms, a node offering services to the outside world is called a real server. (We will use the terms cluster node and real server interchangeably throughout this book.) The IP address used on the real server is therefore called a real IP address (RIP).The RIP address is the IP address that is permanently assigned to the NIC that connects the real server to the same network as the Director. We39。ll call this network cluster network or the Director/realserver network (D/RIP network). The Director uses the RIP address for normal network munication with the real servers on the D/RIP network, but only the Director needs to know how to talk to this IP address.The Director39。s IP (DIP)The Director39。s IP (DIP)