The important limit comes from the size of the host OS will support. Then it is the version on DoT.
LUN size limitations in Windows 2003 SP1
GPT support is available for Windows 2003 SP1 and later versions. Microsoft's statement on this subject is:
The creation/expansion is supported.
The maximum raw partition of 18 exabytes can be supported with Windows file systems currently limited to 256 terabytes each.
NetApp filers currently support 2-TB LUN sizes in Windows 2003 with SP1. SnapDrive for Windows uses MBR disks, so it will not be able to support LUNs larger than 2-TB until it allows the new GPT disks.
However, if the filer is running Data ONTAP 7.1, the maximum LUN size a filer can support is 11-TB for traditional volumes and 16-TB for flexible volumes. FlexVols do not create extra space, so the 16TB volume limit includes components such as parity and WAFL overhead. With both traditional or flexible volumes, space reservations can be turned off and a 16-TB LUN can be created. However, this is not necessarily useful. Even if the LUN is never more than 50% full, the entire 16TB will be used within a "short" period of time. LUN size limitations in Windows 2003 and previous versions
A partition table within the MBR data structure contains information describing how the disk is partitioned. Each entry in the table lists the cylinder/head/sector (CHS) location for each partition, as well as the partition type information. Four-byte fields in the partition table restrict the total number of sectors in the logical unit to (2^32- 1). Thus, under the x86 architecture, the maximum size of a partition using standard 512-byte sectors is 2 TB.