//I am planing to migrate from Aradial to FreeRadius2
//and i currently have 10000 subscribers

A piece of advice: DO NOT deploy Freeradius2 now! I am using FreeRadius 2.1.9 + Mysql 5.3 on FreeBSD 8.1, and the radiusd exits abnormally (although it says "info: exiting normally" by itself ) many times a day!  I have been driven mad! and I decide to revert to freeradius 1.1.8. 
 
Believe me, or you can search "exit normally but unexpectedly" in maillist archive yourself.
 
PS: deployment of freeradius is rather easy. Read its sample configuration files, and you will find them easy to understand.