Seagate has confirmed it will offer a 3TB drive.

As reported by Thinq, the company should announce its 3TB 3.5-inch disk drive by the end of the year, subject to operating system, motherboard BIOS and RAID vendor support.

Disk drives are addressed in 512-byte sectors, logical block addresses (LBAs) as set down by DOS back in the 80s. The system can't assign LBAs in excess of 2.1TB, so you'll need an operating system that supports extended or long LBAs in order to go beyond that point. Windows Vista and 7 offer support, but Windows XP does not, and its users effectively won't be able to use drives with more than 2.1TB capacity, according to Seagate.

Thinq goes on to say that when 2.1+TB drives are used as a boot disk, the master boot record partition needs changing, and that means a new GPT partition table. It also means that motherboards need take this into account and a UEFI standard provides support for both the GPT table and the extended LBA addressing. Unfortunately, most motherboards don't support UEFI - yet.

A fourth constraint is that RAID software needs altering to include 2.1TB+ drives in RAID arrays. Seagate and other disk drive manufacturers are working with operating system, motherboard, and RAID vendors with plug-fest events to make sure the four components in this area work properly together.

Western Digital has its Advanced Formatting scheme to deal with the same circumstance, but it talks about having Windows XP support for the 4096 byte data sectors involved. Each 4096 byte sector appears as right logical 512 byte sectors by the hard disk drive interface. A Windows XP Advanced Format drive installation could mean running a jumper between pins seven and eight on the hard drive before plugging it in.

Western Digital is also catering for other older operating systems as well as XP, with a WD Align facility to align partitions on 4096 byte sector boundaries. Mac OS X Tiger, Leopard, and Snow Leopard can work with 4Kb sector drives, as can Version 2.6.31 of the Linux kernel.

No doubt, the Unix and Linux O/S vendors and Apple will be involved in the 4Kb sector plug-fests, as will storage array vendors with their own controller software, such as NetApp.

Barbara Craig, a Seagate senior product manager, is quoted as saying that Seagate expects to launch the 3TB drive by the end of the year. Our information is that is a 3TB Constellation ES with a 6Gbit/s SAS interface. ®