The storage industry has recently introduced storage devices with capacities which exceed 2TB (2 trillion bytes). In order for a system to fully support capacities greater than 2TB, the device must be initialized using the GPT partitioning scheme to support addressing the full range of capacity. If the user is intending to boot from one of these large disks, there is an additional requirement that the system’s base firmware interface must be using UEFI and not BIOS. This Knowledge Base article outlines Microsoft’s support statement across Windows versions since Windows XP, and the requirements necessary to address the full capacity of these devices.
Note that this document refers to disk capacity in terms of power of two, instead of power of ten, which is the most common designation on storage device capacity labels. As a result, references to “2TB” would be referring to a product labeled as having “2.2TB” of capacity.
Also note that the operating system specific behavior noted in this document also applies to the Server variants of the operating system. Thus, “Windows XP” includes Windows Server 2003 and Windows Server 2003 R2, “Windows Vista” includes Windows Server 2008, and “Windows 7” includes Windows Server 2008 R2.