[CentOS] Squid proxy High Availability

> So i am planned to go for one more  Centos5  server with cluster.Can
> any one suggest me how to design it either i have to go for common
> storage for storing all global files or i need to synchronize both the
> server periodically by  running instance on local disk of both the
> servers.

You could also make them peer caches of one another and you could also use 
Linux Virtual Server .. part of the Cluster Suite to load balance .. 
although you would need to make sure that you have persistence enabled.