Hi Yodying,
I have checked this internally and could find that we have the enhancement raised for this request of disabling caching on a virtual server but this is not possible now.
As we can do it globally as of now and may see this enhancement support in next version release .
Right now this cannot be achieved.
I am checking if we can have some work around on this and will update you.
Meanwhile , please let me know if you have any concerns .