Western Digital claims its newly-announced 2.5 TB and 3 TB Caviar Green hard drives are the largest capacity SATA drives on the market. But WD admits that these bigger drives need a little bit of help working on older systems.
“Drives with capacities in excess of 2.19 TB currently present barriers for PC hardware, firmware and software,”
according to WD’s press release
. To get around these barriers, WD is bundling its new drives with an Advanced Host Controller Interface (AHCI)-compliant Host Bus Adapter (HBA), which will pair legacy operating systems with a driver than can support bigger drives.
The 2.19 TB limit isn’t a problem for 64-bit versions of Windows 7 or Vista, OS X Leopard or Snow Leopard, or many versions of Linux. Really, the problem is Windows XP.
XP (whether in 32- or 64-bit) runs into problems because of its legacy BIOS and Master Boot Record (MBR) partition table, which it in turn carried over from earlier versions of Windows. These allow XP to address a maximum only 2^32 logical blocks at 512 bytes each — for an upper bound of 2.19 TB.
Any 32-bit system (even one as new as Windows 7) has trouble booting into a drive with a capacity over 2.19 TB, but they can work around that limitation for a secondary internal drive. XP can only use these large drives as external drives with special USB firmware that either presents it as a single drive using larger sector sizes or as more than one smaller drives to the host (
this is how Seagate’s 3 TB external drive works
) — or using an internal HBA card, which does basically the same thing.
Still confused? WD has a complete list of operating systems, motherboards and USB bridges that it
supports for its new large-capacity drives
. Meanwhile, if you’re ready to roll and the old 2TB drives just weren’t enough storage, the new drives are available now. The 2.5 TB is $189 and the 3 TB hard drive is $239.00.