I have been putting off building a home file server for more than two years now. I have been patiently waiting for the 2TB SATA hard drives to be surpassed by 2.5TB SATA drives, in the hopes that prices for 2TB hard drives go down to $80 per unit. Needless to say, my patience is running short. It has been more than two years now and hard drive manufacturers seem to have stalled at a 2TB capacity limit for all SATA hard drives.
    
What do you think is causing the stall in hard drive capacity growth? Is it this bad economy? Is it due to Windows XP’s inability to read from hard drives that exceed 2TB? I would really appreciate it if you can provide any insights on when you think this long-standing 2TB capacity limit will be broken with the introduction of 2.5TB hard drives.

—Ivan

There is indeed a 2TB barrier (sorta), but it only applies to boot partitions, not all drives. And not just in Windows XP; it’s a long-standing limitation that is finally being reached by hardware.

Back in the Stone Age, floppy disks were formatted into tiny chunks—512-byte sectors, to be precise. In order to find data on a disk, the drive needs to know where to look, so each sector has an address that the Master Boot Record uses to locate information. The MBR stores disk partition information as 32-bit integers, meaning it can address a maximum of 4,292,964,296 512-byte sectors, or 2,199,023,255,552 bytes. Look familiar? It’s 2.2 tebibytes, or 2TB. Since the MBR can’t allocate addresses to partitions with more than 2TB worth of 512-byte blocks, you can’t boot from them. No problem if you’re booting from another drive, but a bummer for people who really want a massive boot partition.

The solution, as discussed in our June 2010 White Paper, is three-fold. You’ll need a motherboard that uses Extensible Firmware Interface (or EFI) instead of the 32-bit BIOS that’s standard, a GPT-initialized drive (as opposed to MBR), and a 64-bit version of Vista, Windows 7, Linux, or OS X. Only then will you be able to boot from a partition greater than 2TB. Manufacturers have resisted transitioning from BIOS/MBR to EFI/GPT, but as physical drives with more than 2TB of storage become a reality, they may finally have to comply.

So that’s the bad news. The good news is, if you don’t need to boot from it, and just want a storage device that’s greater than 2TB, all you have to do is wait for 3TB drives later this year, as both Western Digital and Seagate are bringing them to market by the end of 2010.

 

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