It’s been nearly two years since we saw the first 2TB drives hit the market. You’d think we would have gotten 3TB drives months ago. It’s not that hard, is it? Turns out, it’s pretty complicated. We’ll get into all that in a second, but in the meantime, here’s what you need to know: Western Digital’s new 3TB Caviar Green drive is the first internal bootable 3TB drive to hit the market. It’s not the first 3TB drive—Western Digital and Seagate both have external versions—but it is the first bootable 3TB drive.
So, why are we only now seeing bootable 3TB drives? Because most computers are running on kludged-together legacy systems, that’s why! Hard drives have historically been divided into 512-bit sectors. Your drive’s master boot record, which tells the BIOS where everything is on a given drive, is 32-bit, so it can only address a number of sectors equal to one 32-bit integer’s worth. Two to the 32nd power is 4,294,967,296; multiply that by 512 bytes and you get 2.19TB, which is how big a partition can be before the MBR runs out of room to figure out where everything is. To overcome this obstacle, your PC needs to meet a laundry list of requirements: It needs a 64-bit OS, a motherboard that supports UEFI (the successor to the BIOS), and support for GPT partitions rather than MBR.
We knew it was only a matter of time before somebody conquered the old 2.19TB partition limit that’s hamstrung drive capacity for the past few years. Since it’s difficult to create a bootable Windows partition on a drive larger than 2.19TB, most vendors have been happily sticking to 2TB drives while waiting for the rest of the computer ecosystem to catch up. But that’s all changing; hard drive vendors are now going full steam ahead on 3TB drives. Seagate and Western Digital already have 3TB external drives, but Western Digital’s four-platter 3TB Caviar Green is the first bootable 3TB drive.
For select values of "bootable."
The 3TB Caviar Green squeezes 750GB onto each platter and boasts 64MB of cache. Its controller is 3Gb/s SATA, not 6Gb/s, but “green” drives aren’t exactly bumping up against the limits of the last-gen SATA spec. But can you use it as a boot drive? And why shouldn’t you be able to, anyway?