Seagate senior product manager Barbara Craig confirmed the firm will announce a 3TB hard disk drive later this year. The creation of this disk was a bit more complicated than just upping the areal density, the original LBA (logical block addressing) standard does not support capacities in excess of 2.1TB so the company had to extend that to Long LBA addressing.
Windows XP will not be supported, to use this HDD you will need a modern 64-bit OS like Windows Vista/7 or Linux, and if you want to use it as your primary HDD you'll also need a motherboard with UEFI support because the BIOS has the same limitation. More problems arise when you want to put 3TB HDDs into a RAID array, because these devices feature the same 2.1TB cap. Making the switch wasn't be easy, but Seagate says many of their partners have attacked the problem, and states about 80 percent of the infrastructure's ready to support it.
However, this presents a big problem, as many standard motherboards don’t feature a UEFI system. Some manufacturers, such as MSI, have introduced UEFI to a select few boards, but UEFI is still not the de facto standard. What’s more, any RAID drivers, if appropriate, will also need to support Long LBA if you want to put your 3TB drives in an array.
Basically, with the original LBA limit set at 2.1TB, it seemed pointless for anyone else to prepare for any capacity beyond this, so we now have a situation where many hard drive controllers, BIOSes, drivers and operating systems are all set with caps of 2.1TB, and this is going to take an industry-wide overhaul to overturn.
More info about the technical hurdles of 3TB HDDs can be read at THINQ.