LVS Heartbeat Ldirectord在RedhatAS4.2上的实现
　　环境描述：
　　本文在配置LVS时使用三台linux，一台做Directorserver (192.168.0.25),两台做realserver(192.168.0.127
192.168.0.12,在配置lvs+heartbeat时又添加了一台(192.168.0.126)做为备份主节点,虚拟VIP:
192.168.0.100

Heartbeat + LVS + ldirectord构建可伸缩网络服务

网络环境：

机器数量：2
操作系统：Centos 5.0，Centos 5.2
机器名：centos50,centos52
机器IP：
Centos 5.0: 10.2.20.15
Centos 5.2: 10.2.20.88
虚拟IP: 10.2.20.17

High Availability

As more and more mission-critical applications move on the Internet, providing highly available services becomes increasingly important. One of the advantages of a clustered system is that it has hardware and software redundancy, because the cluster system consists of a number of independent nodes, and each node runs a copy of operating system and application software. High availability can be achieved by detecting node or daemon failures and reconfiguring the system appropriately, so that the workload can be taken over by the remaining nodes in the cluster.

In fact, high availability is a big field. An advanced highly available system may have a reliable group communication sub-system, membership management, quoram sub-systems, concurrent control sub-system and so on. There must be a lot of work to do. However, we can use some existing software packages to construct highly available LVS cluster systems now.