I have a shiny new 5TB WD Black and was hoping to use it as the OS System disc and for a fair number of audio production programs, Workstations, samplers, synthesizers and such. Moving from a 2TB. The new drive loses nearly 3 TB as "unallocated space" if run direct from the Win7 program disc. I reset the drive, initialized it in GPT, got back all 5 TB but can't put the OS there. Do any newer versions allow this or do I go backwards to a 4 year old 2 TB that's in the habit of crashing to bluescreen at least daily and use the new one for all programs but windows? (I'm backing the old drive up using Acronis in total as I type, (tired of rebooting ). Win 10 upgrades are free right now...will this change allow me to increase the storage on my system while using a new drive for the system? Old format has 2TB OS + programs, 3TB full of samples, 2 x 3TB as RAID backup system, too many usb drives to list when I need to empty stuff out......Thank in advance!

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    Windows already supports this, just use GPT, x64 versions of Windows 7 also support it. A RAID isn't really a backup system – Ramhound Feb 7 '16 at 3:50
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    @Ramhound if OP has a BIOS based system (rather than UEFI) then booting from a GPT disk is out of the question. Windows installer refuses to accept GPT as a valid scheme for the boot disk on BIOS systems. – Mokubai Feb 7 '16 at 9:35

You haven't said how old your motherboard is, or what features it supports. Mokubai may be correct, but if your computer was introduced in mid-2011 or later, it may already use UEFI firmware, which supports booting from a GPT disk. Even a few older motherboards use EFI. You'll need to re-install in EFI mode, though; most EFIs include a Compatibility Support Module (CSM), which enables them to boot in BIOS/CSM/legacy mode. It sounds like you're using that now (or have an older BIOS-only motherboard).

If your motherboard is an older BIOS model, you have a few options, most of which you won't like:

  • Use only 2TiB of your disk's space.
  • Return the disk and get a smaller ~2TB disk to replace it.
  • Split the disk such that one to three partitions fall entirely under the 2TiB mark, and one final partition extends from just under the 2TiB mark up to just under 4TiB. This will enable you to use most of the disk, but it's awkward and at least a little risky. Although Windows 7 works with such disks, some utilities may fail -- possibly disatrously. Personally, I wouldn't go with this option; I mention it only for completeness.
  • Use a second, smaller disk, in conjunction with your 5TB disk. You can boot from the smaller disk and use the 5TB disk as a GPT data (non-boot) disk. If you have the funds, a small SSD can make a good boot disk, since it will be a fast place for the OS itself to reside. If not, you can dig up an old ~60GB disk that should be plenty big enough to hold Windows.
  • Use Clover or DUET to put what is essentially an EFI-as-a-bootloader on your disk. You should then be able to install Windows in EFI mode and use the whole disk. This solution is a good way to "have it all," but it requires comfort with unusual low-level tools to set up and it doesn't work on all systems. In particular, AMD CPUs work poorly, although Intel CPUs work better. Clover is designed as a Hackintosh boot loader, and so requires access to OS X to begin to use it. (You should be able to put Clover on a USB flash drive to get started, then transfer it to your hard disk.) DUET may be better if you have no access to OS X, but Clover has an active community supporting it, so I'd use it if at all possible. Neither option is good for a non-geek; you must have pretty high "geek creds" to use either tool.

You should NOT continue to use a failing disk. Such disks may be sort-of kind-of usable for a while, but sooner or later they're likely to fail catastrophically and with *no warning."

Overall, the two-disk solution is probably the best one, provided you have space in your computer for two disks.

  • From experience your option 3 (splitting the disk into 2TB and 2TB) does not work, you can literally only get the first 1.7TB and then the rest of the disk is unusable/unpartitionable under MBR. You have to partition the disk as GPT to get the full size of the disk and then that will preclude you from using it as a boot device under BIOS based firmwares. The wikipedia page on MBR seems to suggest this should work, but I was unable to get it to happen. Using a second disk is least kludgy and most compatible. – Mokubai Feb 7 '16 at 16:49
  • I've done it, albeit only with a virtual disk under QEMU. I don't recall what I used as my partitioning software. This page describes my limited testing with this configuration. I agree that it's a kludgy, and even a somewhat risky, solution. – Rod Smith Feb 8 '16 at 2:21
  • Actually, the motherboard is an ASUS Sabertooth 990FX UEFI based unit. I should have no such problems. Unlocked overclockable 8 core AMD CPU, 4.15 GHz, without overclocking it, 32GB RAM. Already a 64 bit machine. I'm not that worried about drive contents as I have cloned it all off to redundant USB drives ranging from 2 to 4 TB each...but the crashing is annoying and stops me in the middle of too many projects. I see that the chart above says that this configuration should work....except for making it the boot disk. The motherboard runs at least 7 hardware drives inside, plus many USB's. ... – Daniel Boyd Feb 8 '16 at 2:25
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    If you've got EFI firmware, then you should be able to install in EFI mode. That last bit is the critical part, since it's not always obvious how to control the boot mode. See this page for a tutorial on installing Windows 7 in EFI mode. You may also want to see my page on the CSM. It's Linux-centric, but describes the principles behind the CSM and why it can cause problems. – Rod Smith Feb 8 '16 at 2:29
  • @RodSmith it could be that my problem was using the built in Windows partitioning tools or allowing them to create a partition at maximum sizes which could block the creation of the next needed partition. In either case it sounds like your answer is the correct one in this case and this is not (directly) a BIOS problem. – Mokubai Feb 8 '16 at 9:45

Quite simply your motherboard is too old. Buy (or use) a smaller drive as your boot disk and use the new one for bulk storage.

From Table 3: Windows support for combinations of boot firmware and partitioning schemes for the boot volume at Windows support for hard disks that are larger than 2 TB Microsoft does not support BIOS + GPT as a boot volume, nor does it support UEFI + MBR. You either use BIOS + MBR (limited to <2TB boot disk) or you make sure your firmware is UEFI based and use GPT with full large disk support.

System        BIOS + MBR   UEFI + GPT                  BIOS + GPT                   UEFI + MBR
Windows 7     Supported    Supported; (64-bit only)   Boot volume not supported     Boot volume not supported
Windows Vist  Supported    Supported; (64-bit only)   Boot volume not supported     Boot volume not supported
Windows XP    Supported    Not supported              Boot volume not supported     Boot volume not supported

I fought this a short while ago and found out that while Windows itself supports GPT disks, it does not support booting from a GPT disk on a BIOS based system. If you want to use your disk to boot from then you need a UEFI based motherboard.

Linux seems to be able to work around this, but Windows doesn't seem to care to.

The only reliable way around this restriction is to use a <2 TB disk as your boot/system disk, Windows is perfectly happy using a GPT disk as a bulk data disk without BIOS involvement. I ended up buying a 240 GB SSD then installing and booting from that.

PC World has a nice article describing the problem: Everything You Need to Know About 3TB Hard Drives

Essentially though, the MBR partition scheme cannot support disks greater than 1.7 TB, and BIOS does not support booting from anything other than an MBR disk. There are workarounds but they're all horrific kludges and will block you from installing Windows.

I actually managed to make one of the kludges work, but it only worked until Win10 threshold 2 was released. The th2 installer basically ran the full operating system install from scratch and it was at this point I was unable to upgrade because the installer didn't "see" the disk as valid in able to update itself.

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