The 2TB Barrier

Pretty much all HDDs (and SSDs) are addressed using a scheme called Logical Block Addressing (LBA). The method is very, well, logical. Storage is addressed linearly, regardless of how the hardware itself is accessed. You start at LBA 0 and you go all the way up to the last address in your device. The number of LBAs you can address is a function of your hardware and the style of partition you’ve applied to your drive.

Master Boot Record partitioning is by far the most common on PCs today. LBA 0 contains the Master Boot Record (MBR) and your BIOS looks at the contents of LBA 0 to determine how and what to boot.

Now LBAs under MBR partitions are addressed using 32-bit values, the maximum of which is 2^32 or 4294967296. Each LBA on a hard drive corresponds to a 512-byte sector value (even on current 4K advance format drives, they still appear as 512-byte sector drives to the OS), so the largest partition you can have in a MBR partitioned drive is 4294967296 * 512-bytes or 2,199,023,255,552 bytes.

Hard drive manufacturers define 1TB as 1 trillion bytes. If we use that definition then the largest 32-bit MBR partition would be 2.199TB (2,199,023,255,552 bytes / 1,000,000,000,000). If we define 1TB as 1024^4 bytes (TiB) then the largest 32-bit MBR partition would be 2TiB (2,199,023,255,552 bytes / 1,099,511,627,776). Either way, with a 3TB drive there’s no way we’re getting a single 3TB partition using MBR.

In use on all Itanium and Intel based Macs (among other systems) is GPT (GUID Partition Table), and a feature of GPT is 64-bit LBA support.

With 64-bit LBAs the largest 512-byte sector drive we can address is 9.4ZB (Zettabytes - 10^21 or 2^70 bytes depending on if you’re counting in base 10 or 2). That’s an absurd amount of data.

GPT drives are supported as data drives in all x64 versions of Windows as well as Mac OS X and Linux. Below we have some screenshots of creating a GPT drive in Windows and OS X:

GPT Partition in Windows 7

GPT in Mac OS X

You’ll note that I said data and not boot drives. In order to boot to a GPT partition, you need hardware support. I just mentioned that your PC’s BIOS looks at LBA 0 for the MBR. Your BIOS does not support booting to GPT partitioned drives. GPT is however supported by systems that implement a newer BIOS alternative: Intel’s Extensible Firmware Interface (EFI).

Intel based Macs don’t use a BIOS and instead have an EFI which allows them to boot to GPT drives. Most PC motherboards however do not have EFI support, and those that do may have bugs associated with the implementation.

Case in point is Intel’s DX58SO, which just happens to be my default storage testbed. The good news is that Intel has deployed EFI on many of its motherboards. The bad news is the DX58SO (and potentially other models?) has some serious issues when you enable EFI.

The biggest problem I had was USB support dropping out completely when I enabled EFI on the Intel board. This is apparently a known issue and doesn’t affect all USB peripherals, but it prevented my keyboards and mice from working - which also meant that I couldn’t install Windows.

To make matters worse, even with EFI disabled I couldn’t get a 2TB partition created and installed to. The Windows 7 installer would simply complain that it couldn’t be installed to that drive.

There’s an odd bug with the DX58SO that lets you create a single 3TB partition with the SATA controller in Native IDE mode, and with that you can complete a full Windows 7 install. Note that in Native IDE mode you lose performance benefits like NCQ so it’s not ideal, but it’s the only way to get the drive with Windows installed on it.

Intel is aware of the bug and is working on a solution. Apparently the DP55KG board should work perfectly fine but that didn’t help me in this situation. Update: Intel has since sent me a beta BIOS that addresses a number of these issues, I'm playing with it right now but it didn't make the cut for use in this review. Thankfully it looks like Intel is aware of the problem and is actively working on a solution. I've also asked Raja to pay closer attention to EFI support in his motherboard reviews going forward.

My experience with the Intel board and installing Windows with this 3TB Seagate drive pinpoints why we don’t have an internal drive option for the 3TB Barracuda XT: the hardware isn’t ready for it yet. Consumers are used to buying a new hard drive and just sticking it in their system. With the requirements for EFI and GPT, we’re going to need a lot more effort from the motherboard manufacturers and clear messaging from the drive makers to avoid a lot of confusion in the marketplace.

Not Just Another Upgrade 3TB Internal Drive Performance - Nothing to Get Excited About Yet


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  • Aikouka - Monday, August 23, 2010 - link

    There is a 120mm fan running air over the hard drives in question and there is an actual space in between the drives... they are not literally sitting on each other.

    The case is a Lian Li PC V2000B which has room for 10 HDDs in a 5x2 array. Optimally, I tried to leave an empty (HDD) space between each drive, but this was not entirely possible, so I had to not give them extra "breathing room."

    While my spiel is technically purely anecdotal at best... I have similar WD drives that are working just fine and the one that was producing file read errors and hanging on reading files was the one that sat directly above the Seagate "Inferno." It is probably good to note that the WD drive was also one of their "Green" drives, which I assume also has lower temperature thresholds given that its a 5400RPM drive.

    I still do run other Seagate drives in my PC, but I believe that they have that extra "buffer" between them and other drives now.
  • pcfxer - Tuesday, August 24, 2010 - link

    Get some sexy hot-swap drive-bays for the 5.25" external slots. That way when you *need* the hot-swap compatible drive ccontroller you are set to show off your ZFS awesomeness. Reply
  • mewgirl - Monday, January 31, 2011 - link

    There is a brand called i/O that lasted as long as I had it until it was stolen, never gave a single error, and connected properly to every computer I plugged it into, without having to go into disk manager, run commands, etc., to plug in. And MOST BENEFICIALLY it didn't come with any files on the disk. So (I don't remember the size of it), if it was a 300GB drive, then, when I plugged it in, it ACTUALLY SAID 300GB. It didn't even say 299.7. It said 300. If I remember correctly there was a scattered file or two on it, but I didn't think they were programs (but could have been wrong - notice I didn't even know what the double-cord was for at the time), and they didn't try to initiate themselves. But all it took to delete them was to hit "delete". And then it was listed as a full 300GB drive (or whatever size it was).

    Although, that particular brand name is a bit hard to Google. This was back when Google was actually a search engine, about 2 years ago (as in, it had other products, but the search engine actually worked?), and it took a while to find their website then. Which was done to find out why it came with an extra USB plug on the cord... one of those drives that has two USB plugs so you can plug in both if using only one makes it slow. AND it warns about overheating "only use both if you're having trouble". ANOTHER thing that is never done by other companies.

    Then the Target closest to my dad;s house stopped selling it and I could never find it again.
  • loekf - Monday, August 23, 2010 - link

    Call me biased, but I have used several WDC MyBooks and they never let me down. They have more room for ventilation. A few weeks I had this drive (2 TB) and after one day I had seen enough.

    Poorly designed, never wanted to go into standby/sleep mode and overheating.

    Yes, you can disable the sleep mode, but then IT IS ALWAYS spanning when attached to your PC and Windows up and running. Even when you power-down your PC and you leave the drive connected to the mains, the drive is so stupid to power up again by itself.
  • ricamiller - Monday, August 23, 2010 - link

    Why couldn't you just remove the hard drive from the case and insert it into something like a Thermaltake docking station with esata?

    There's no enclosure so wouldn't this solve the heat problem?
  • Drag0nFire - Monday, August 23, 2010 - link

    Yeah, this confuses me too. But it's not just Seagate. All external manufacturers are doing it, from big names (Seagate, Samsung, WD) to off-brands (Fantom, Cavalry). Market factors push for a drive that is small (no space for air ventilation) and cheap (no money for quality metal materials to radiate heat).

    I recently had to RMA a Samsung HDD for this reason. Small package, no ventilation. It would heat up to 55C and then the SMART would register read/write errors. And this was a "low-power" 5400RPM drive!

    I bought a WD green drive in an enclosure. Doesn't solve the heat problem, but those drives are pretty hearty and I'm using it only for backup. If I were to use it more extensively, I think the only solution is to buy a HDD and enclosure separately.
  • designerfx - Monday, August 23, 2010 - link

    because they're too busy marketing external drives as the next best thing, when people don't realize how horrid most external drive solutions are when it comes to temperature.

    Not only that, but it's a humorous double win for HDD manufacturers (and double loss for consumers). They're charging you *more* than to buy it with an enclosure , and it will burn out years faster! double win as far as money goes.

    2TB internal: $100 now. 2TB External - $125-150 (enclosures are a piece of plastic that costs them next to nothing to manufacture and they are usually priced at 25-50).. Not only that, but if the enclosure doesn't support USB3 or Sata2, you might lose it (even if the internal hard drive supports it).
  • jjzeal007 - Thursday, September 16, 2010 - link

    Remember Google's study of 100,000 SATA/PATA hard drives in its data centers?

    One conclusion: There isn't as much of a correlation between drive temperature and failure rate as might be expected... excessively cooled drives actually failed more often than drives that ran a bit hot.
  • Wolfpup - Thursday, September 16, 2010 - link

    Yeah, I'm just baffled by how products like this keep getting released to the public by tech companies. That's COMPLETELY unacceptable.

    What's nuts is in every other way it seems perfect for what it is! I was interested in buying one until getting to the heat issue
  • taltamir - Wednesday, October 20, 2010 - link

    engineers can only point out problems and solution, management then decides NOT to implement them to save money.

    In the xbox RROD, the xbox scratched disks, and many other cases there are documentations showing that the engineers pointed out the problem and devised a solution... management decided its not worth the money and that they know better.

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