5 1. Introducing 1.uNderstanding the Layers of High Availability FIGURE 7.1 Each layer has its own App App App App Application layer forms of high availability H|&: perating Virtualization software Virtualization layer 一一一一一一一一一一一一一一一一一一一一 Physical infrastructure(switches, NICs servers,SANs, disks, etc. Physical layer 河南中医药大学/阮晓龙/13938213680/htp/cloudxg.hactcm.edu.cn/http:/www5ucwebcn