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


View All Comments

  • Belard - Monday, August 23, 2010 - link

    ALL brands have their bad batches. Maxtor, WD, Hitachi-IBM, etc... and even intel.

    I have used lots of Seagates and Maxtors with good reliability. Yes, I've had failures - but not really any more than WD.

    In the OLD days, Seagates were called "Sea-crates" typically used in cheap PCs ($2000+ computers) - I'd never touch those junky RLL drives. I bought Quantum SCSI drives which were higher end, more reliable and costs more money... and being SCSI - they were much faster. I miss Quantum. :( Today, I buy Seagates - they are easily quieter than most drives - with only Samsung just as quiet.

    I still buy 1TB Seagates. I don't trust the 1.5~2TB drives from anyone. But the tech used in 2~3TB drives are filtered down to the 500GB drives (single 500GB platter) - so the density reliability issue is there - but the less-parts (heads and arms) factor does help. So todays 500GB drives are very thin... wow! ;)
  • mewgirl - Monday, January 31, 2011 - link

    ....But since WD is THE WORST manufacturer of external hard drives, this post means you are definitely NOT recommending Seagate, then, correct? Reply
  • mino - Monday, August 23, 2010 - link

    You should NEVER use an on-demand cooling system with magnetic storage.

    Hard disks are an order of magnitude more sensitive to temperature changes than pure high temperatures.
  • Jonathan Dum - Monday, August 23, 2010 - link

    Interesting. Proof to back up that claim? Reply
  • has407 - Monday, August 23, 2010 - link

    The OP is nominally correct. While I wouldn't go so far as to say "NEVER use an on-demand cooling system", I'd say they're likely to do more harm than good unless carefully engineered and integrated with the HDD.

    Rapid changes in temperature can kill a drive faster than elevated temps due to, e.g., thermal expansion/contraction of components (heads, platters, spindles, etc.), and air density changes which affect head ride height.

    Those changes require active adjustment and compensation, and are necessary and common in today's drives/controllers. However, there are limits. Drive manufacturers specify a maximum temp change/time (even if it may not show in the data sheets available on their web site).

    The best solution is to maintain a steady and moderate temperature change. The worst solution is a typical/cheap "bang-bang" controller that starts/stops when temperature limts are reached, and which causes rapid changes in the drive's temperature.

    Case in point: The absolute worst thing you can do for your laptop drive after leaving it in the car for hours on a frigid day is drag it into a warm room and immediately start pounding on it. Virtually guaranteed to result in errors and reduced life (if not short-term failure).*

    In short, active cooling is not necessarily bad, but stupid active cooling that causes wide temp swings over short periods in the drive can cause far worse problems than allowing the drive to run at an elevated and slowly changing temp.

    This has been a problem for many years, and increasingly as tolerances decrease (especially with higher track densities). While drives/controllers continue to adapt and improve, it's still a significant factor, and the larger the media the worse the problem. For recent papers (sorry, don't have any recent freely available links), see:

    * Yes, people talk about the "freeze your HDD" to try and recover it. (It may even work--never tried it.) But subjecting an HDD to that kind of rapid temperature change abuse even occassionally is guaranteed to kill it in short order.
  • JonnyDough - Monday, August 23, 2010 - link

    It makes a lot of sense, even without the links. The hardest thing on a car is starting it in the dead of winter when there's no oil up in the engine. It grinds, and then as the friction causes it heat up quickly with cold oil it continues grinding until it is warm and coated in oil internally. Reply
  • mindless1 - Monday, August 23, 2010 - link

    That is wrong. If you have a constant speed/always-on cooling system, it means that the drive changes in temperature as it wakes up, reads and writes, and more as it keeps running.

    If you have on-demand, as the drive starts to warm the fan kicks in and keeps the drive at a more constant temperature, including increasing fan RPM as needed to keep the drive at the same temperature! Plus, with on-demand all those times you are not using the drive and it is sleeping and at low temperature, your fan isn't pulling in dust to clog up things.

    Also, it IS high temperature that does damage. Granted, yes it has to change temperature to get to a high temp, but the more the temperature changes the more the different coefficients of expansion come into play. For example, you can stretch a rubber band all day long, but if you stretch it too far it starts to rip apart.
  • Belard - Monday, August 23, 2010 - link

    This or anyone else... should have minded the heat problems. There are external cases for HDs that have an 80mm cooling fan - low RPM.

    My Seagate drives in my case (1TB) are currently 39c... I run my fan at LOW speed to keep the noise to pretty much silent. A drive hitting 50c+ would make me nervous... 60+ is VERY bad!

    And for a 3TB drive holding that much data, RELIABILITY is most important! USB 3.0 and such are important features when moving that much data and it'll slow down when you're using the drive for what it is intended?!


    The dock is a handy, but a wider one would be nicer... there are other dock-drive designs out there, some with dual docks. Generic versions that allows you to put in ANY drive would be the way to go. OR better yet... use the HOT-SWAP abilities of eSATA and pop your drive into a drive bay on your computer - NO DOCK NEEDED!

    Theres about 60+ options on Newegg. Many docks, you just plug in your drive - sans case.
  • Aikouka - Monday, August 23, 2010 - link

    Heat problems are one of the reasons why I'm starting to shy away from Seagate drives after using them for a few years. A few months ago, I noticed that one of my WD 1TB HDDs was exhibiting some odd file read issues. When I opened up my server, I found it right above a Seagate 1TB HDD, and when I tried to pull the Seagate drive out, it was almost too hot to touch!

    Of course a (mechanical) hard drive will produce heat, but the Seagate seemed to be in a league of its own compared to all the other drives in my file server. I'm really not sure what brand to even go with now... I purchased a Samsung drive based on recommendations, and that drive died after only two months (the whole random disappearing act leading to refusing to ever show up). I recently purchased a WD 2TB drive that came up clean in a full-disk error check, so we'll see how that goes!
  • mindless1 - Monday, August 23, 2010 - link

    Your server is not set up correctly, blame it not the drive. A proper case configuration for stacked drives leaves at least 1cm or so between each and ample cool intake airflow through the drive rack. In that scenario you will have no problem cooling any 7200 RPM drive, or with higher airflow rate, 10K RPM drives too.

    Also, there is not a significant difference in operating power or running temp of equivalent drives from Seagate vs other brands. Single-digit # of degrees is not enough to matter one way or the other till you reach the upper limits.

Log in

Don't have an account? Sign up now