If you are using VMWare ESX or ESXi and have a single disk array that is 2 terabytes or larger, you are SOL. You can’t use all the space.
See this link: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=3371739
However, if you can reconfigure your raid array to have multiple volumes of less than 2 terabytes each, then you can use extents to take advantage of the space!
If you don’t know about extents, see this link: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2000643