主题：About load ballance server -- ppw

Server Clustering allows a group of servers to intelligently service requests made to a host name. This high performance architecture allows for significantly greater performance than can be achieved by a single server.

In addition, if any of the services on a single server fail, the requests will be automatically routed to the remaining server. As a result, downtime related to server failures or administrative maintenance can be significantly reduced or eliminated!

The servers are in pairs, and each physical server has 4 IP numbers. Also, in addition to the IP addresses bound to the physical servers, there are an additional 4 virtual IP addresses configured on the load balancer.

When HTTP, FTP or SSL requests are made to any of the virtual IP numbers, the load balancer sends the request to one of the physical servers, provided that server is "up" on that service port. If the server is not responding to that service port, all requests will be automatically sent to the remaining server.

Examples:

IPs on Server #1 IPs on Server #2 Virtual IP Protocols

192.168.1.2 192.168.1.6 mapped to 192.168.1.10 HTTP, FTP, SSL

192.168.1.3 192.168.1.7 mapped to 192.168.1.11 HTTP, FTP, SSL

192.168.1.4 192.168.1.8 mapped to 192.168.1.12 HTTP, FTP, SSL

192.168.1.5 192.168.1.9 mapped to 192.168.1.13 HTTP, FTP,

a) Create DNS records pointing towards the virtual IP addresses:

Virtual IP

www.widgets.com 192.168.1.10

ftp.widgets.com 192.168.1.11

secure.widgets.com 192.168.1.12

b) Create identical web sites, FTP data and SSL sites on both servers and bind the HTTP, FTP and SSL services to IP addresses as follows:

Server 1 Server 2

HTTP service 192.168.1.2 192.168.1.6

FTP service 192.168.1.3 192.168.1.7

SSL service 192.168.1.4 192.168.1.8

c) Clients communicate to the server cluster through the virtual IP numbers, and the supported requests are balanced across both real servers by changing the destination address at wire speed:

这个webapplication怎么在两个server间sync.呀. 感觉上挺悬.

解决方法1.

NFS? 一个mount在另一个上.

解决方案2.

用distribute的database.

可行么?