The largest new desktop SATA hard drives on the market have capacities of 3 TB and 4 TB.
This is great for storage, not so great for older machines because it goes beyond what SATA interfaces on older (mid 2011 and earlier) PC motherboards were designed for.
What happens if you try to use a 3 TB or 4 TB drive with an incompatible machine or enclosure, is that it may format to only 800 GB or 2.2 GB, or it may crash and say the volume is unreadable.
PCs that use traditional BIOSes are limited to a directly connected SATA drive of 2 TB or less – they will fail if you connect a 3TB drive. This is a problem with the SATA controller addressing the drive sectors, and is not fixed by partitioning the drive into two partitions smaller than 2 TB.
PCs and motherboards that use the more recent UEFI BIOS can support 3 TB and 4 TB drives directly from the motherboard SATA and eSATA ports, as can recent model PCI-e SATA interface cards (check with manufacturer to verify).
The motherboard’s SATA size limitation is not a problem for USB and Firewire connected drives, only for SATA and eSATA drives. (Important: the USB or Firewire enclosure itself will have to be compatible with large drives however, see External Drives below)
MacPro machines with OSX 10.5 and above support large drives partitoned as GUID Partitioning Table (GPT) when attached to the internal SATA ports.
The Apple Pro RAID card however is limited to drives under 2.2TB each on its SATA connectors even if it is installed in a MacPro. There is no fix for this.
PowerMacintosh G5 machines also have limitations with drives larger than 2 TB, with a few exceptions – when the drive is formatted as GUID, and when the PowerMac is running OSX 10.5 and above, they should work.
Whichever OSX version you have, make sure you are current with the latest updates.
Intel iMac machines should be compatible, although they have their own unique issues with temperature sensors when installing third party drives.
External USB/Firewire/eSATA SATA hard drive enclosures, Multi bay RAID enclosures and Network Attached Storage (NAS) enclosures may or may not support large drives depending on the chipset and firmware of the enclosure, it will have to be verified on a case by case basis. Many of the newest 3.5″ drive enclosures can support 3 and 4 TB drives.
Just because an enclosure has the same model number as another, doesn’t mean that the two enclosures have the same firmware (or even bridge board hardware) internally.
In some cases (such as OWC Mercury enclosures) there is a small switch inside the enclosure of “Advanced Format” or “Large Block Size” which must be turned on to enable compatibility with drives larger than 2 TB. Refer to the owners manual or the manufacturer’s website for specifics.
In other cases, the firmware of the enclosure’s bridge-board chipset has to be updated to make it compatible. Refer to the manufacturer’s website for specifics.
Keep in mind that a drive that has both USB and Firewire interfaces actually has two independent bridge chips inside, one for each interface, and it is possible that one interface works properly while the other does not.
Drives that have eSATA connections have a third path – the eSATA connection does not use a bridge or a controller within the enclosure, it is dependent on the SATA controller of the computer (or of the eSATA interface board in the computer). So again, an external could work on eSATA if the computer’s controller is compatible, and still fail on USB and Firewire with the same drive.
There are two issues to be addressed, the total drive size, and the size of the sectors on the drive.
Larger hard drives (including a number of 2 TB models such as the Western Digital Caviar Green 2 TB) use a new, larger 4 KB sector size, and older machines may not be compatible, or may need software drivers to address the drive.
Western Digital, installing 2 TB Advanced Format drives with Windows http://www.wdc.com/en/products/products.aspx?id=120#tab10
Western Digital, installing 2 TB Advanced Format drives on non-Windows systems http://wdc.custhelp.com/app/answers/detail/a_id/5655
“If your operating system is either Windows 7 or Vista, WD recommends using the latest Intel driver version 9.6 or later for maximum performance in all situations.Please visit Intel for the latest driver downloads.”
For NVidia chipset machines, Microsoft has released a patch for Windows 7 and Server 2008 http://support.microsoft.com/kb/982018
Western Digital has WD Align software to properly set up 2 TB Advanced Format drives with Windows. Note that these software updates do not allow a 3 TB or 4 TB drive to work with an older BIOS motherboard.
Seagate has an information page and links to their DiskWizard software http://www.seagate.com/support/downloads/beyond-2tb/
They indicate that a 3 TB or larger drive used as a boot disk in a machine with an UEFI BIOS needs Windows 64-bit to boot.
Seagate apparently had a problem with their GoFlex 3 TB drives and Apple OSX 10.7.2, which was resolved with OSX 10.7.3
Hitachi has a technology brief on advanced format drives available as a PDF
Windows XP, Server 2003 and Windows Home Server require alignment software for partitioning.