Windows Domain Controller on Hyper-V

Hi,

     Now that we are planning to virtualise our Domain Controllers. we are going to use Hyper-V for the same. 

what are all the basic points that i need to keep in mind before planning to virtualise. there are six domain controllers

1) when we set up DC on a Virtual platform, will hyper V can with stand the maximum I/O operations 

2) consider we are going to user Hyper -V cluster where it goes as Active - Active cluster

Gowsic