I've found you want to use basically the same req's as physical. Your app server is the most critical. I've found somewhere around:

4-8 procs, 12+ GB RAM

Obviously, your mileage may vary (deployment size, console/web users, etc)

I've seen many deployments with less than this, and it's obvious.

For managers, you can easily go lower.

For some other Symantec products, the sizing guide mention: there is 20-30% performance decrease if running on VM, how come CCS doesn't have this issue?

on VMs the IO process would be high hence assuming 20-30% lesser performance than physical machines.

thanks for your info. that means still take into consideration. why no VMWare guide for CCS? Many other products have