Why can I not allocate space on my hard drive?
Question by Al Atherton /

I installed a SECOND hard drive of 3 TB in my HP machine. When I formatted it, the computer automatically partitioned it TWO. One partition, of 2024 GB, it lettered E and everything is ok. The remaining partition, is 746.52 GB and is labeled UNALLOCATED, and is unusable.

The computer sees the space, but won’t allow it to be formatted, or give it a letter. In the Computer Management utility, under Disk Management, all the drives have a heavy blue line above their enumeration, but this 3TB drive is divided and the UNALLOCATED space has a heavy BLACK line above it, and diagonal hash lines thru the field, and says 746.52 FB and Unallocated.

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Answers (17)
  • Skanda

    I have the same problem with my 3TB hard drive I have 100GB partition I installed Win7 and I have 1948GB second partition and I have 746GB I can do nothing shows as unalocated. Is there any way I could fix this without deleating my 100GB partiont I have installed the OS Win7 ?

  • joneric wennerstrom

    I bought a 3T external hard drive and tried to format it, but I ended up with a 2T partition (MBR) and 750G unallocated space. After spending an hour trying to use the windows 7 tools (disk management, diskpart, format, etc.) to configure the 3T drive as one contiguous partition to no avail, I read about EaseUS Partition Master Home Edition in my online search for an answer. In less than 2 minutes, I had my external hard drive all set up to be a 2.73T NTFS (GBT) drive. Once again Microsoft sucks. Seriously, how are they still in business? They can not possibly compensate me for all the wasted time and energy I have lost over the years because of their crappy software.
    Anyway, the EaseUS app was incredibly fast and easy to use. It does what Microsoft should have done in the first place. I highly recommend this app if your having problems partitioning/configuring your hard drive. It saved my hard drive.

    • skanda

      I have the same problem with my 3TB hard drive I have 100GB partition I installed Win7 and I have 1948GB second partition and I have 746GB I can do nothing shows as unalocated. Is there any way I could fix this without deleating my 100GB partiont I have installed the OS Win7 ?

  • Subodh

    I have a ASUS X53U laptop, as my HDD crached i got a new 320GB HDD and the service centre guy just made 2 partitions in it and installed windows 7 ultimate. I just deleted all partitions and then tried to create new partitions, when i created a first 30 GB partition windows itself created a 100mb partition (This was something new for me as i have installed windows 7 from same DVD so many times and this was the first time windows created a 100 mb partition by itself), then i created 2 more partitions of 65GB each, after which when i tried to create 4th partition the something 139GB unallocated space doesn’t give a option to create new partition. Tried deleting and creating the partitions multiple times in different ways but doesn’t help.
    My HDD doesn’t have any data and not even a operating system, so wondering how to fix this

  • manish

    an error ocar during i allocate the nallocate disck space of my external hard drive

  • Aimon Cruz Parro

    I got it. the device is offline thats why i cant see it.. then when i go to disk management i see the unallocated space. 930gb bat it is color black.. the format option is still not click-able. right now im planning to format the device using dos command, but im really confuse now on how to do it. because i really forgot how to.. hope u can help me again thanks.

  • Anonymous

    try Easeus partition master
    http://www.partition-tool.com/product.htm

    • Alxatherton

      I did the GPT conversion.  Works fine now, shows 2.7-something TB, no unallocated space indicated.  Only hassle was the need to empty all data off the physical drive before converting, of course.  ‘Took all day, to move almost two TB.
      Then just used the built-in Windows 7 capability and menu to convert it to GPT. 

    • Anonymous

      Thanks for replying and telling your method to save the datas, important they are and can represent months or years of work. Prior to use again the hard drive check the health with SMART tools.

    • Millaire_s

      Easeus partition master 8.01 server edition let you see full hard disk and is working with a 3tb on rt-n56u asus router plug in usb, I split 3 partitions of 1tb with great result.

      I’m very happy to have find a way with rt-n56u that is supposed to be limit at 2tb Asus give me a job.

  • Mike

    Which operating system are you running?

    For Windows 7 and Vista you have to format it in GUID Partition Tables (GPT) to use the entire 3TB as storage.
    For Windows XP you need a special driver to use the entire 3TB.

    http://seagate.custkb.com/seagate/crm/selfservice/search.jsp?DocId=218619 
    http://www.ghacks.net/2010/11/04/how-to-use-3tb-hard-drives-on-windows-xp/ 

    • Al atherton

      It’s Windows 7 Home Premium, …. thanks for the answering, but it confuses me, the GUID partition doesn’t seem to be necessary according to the website’s instructions.  Could you elaborate ….

    • Mike

      Yes and No.
      By default most computers use the Master Boot Record format which has a disk size limit of 2.2TB. 

      There are ways around this issue:
      – using a sector size of 4KB (usually 512 byte) but that only works if the drive is connected in AHCI mode and the controller supports the translation of 4KB into 512byte sectors

      – using a driver like from DiscWizard which will allow you to create one partition with 2.2TB and a second one with the remaining 800GB (this is done by using a virtual drive with a second MBR)

      – using the GUID Partition table which does not have the 2TB limitation (since Windows XP does not fully support it you require a loader like the one from Paragon)

      Since both, Windows 7 and Vista support the GUID Partition table by default the easiest way around the issue is using GPT on those systems. 

      If you were to boot from this drive several other limitations would apply too (64bit OS, EFI motherboard).

      What you have to do to use the full 3TB as storage:
      1. open up Disk Management
      2. delete all partitions on the 3TB drive 
      (this will delete all data on them, backup if needed)
      3. right-click the drive where it says e.g. “Disk 2, Basic, 3.000GB” and select “Convert to GPT Disk”
      4. create a new partition which can now be the full 3TB

    • Aimon Cruz Parro

      hi hope you can also help me…
      the problem is i have a 1000gb buffalo portable hard drive, but it only shows 237mb. when im inserting the hard drive it only shows CD drive (K:).. i try to go to disk management but i cannot see any unpartitioned space as well. and the available option only is, open, explore, change drive letters, properties. the format is not highlighted.. pls help me guys..thansk

    • Mike

      I believe this (virtual) CD-Drive should contain some driver or software you have to install.

      Once that is done you should be able to see and use the actual drive space.

      I suggest to read the manual or take a look at the Buffalo support section about that.

    • Aimon Cruz Parro

      yap there is, before i can acces it, but now it always having an error, the device may not be recognized properly. open my computer and make sure the drivers are added to your computer properly. if the drivers are not added properly, reboot your computer and run the set up again.
      when i see my computer the device isn’t there only the Cd-Drive is there. even in disk management. i’ve tried to reboot and reconnect connect my device into a different hub, but still the same problem.

       

  • Mike

    Which operating system are you running?

    For Windows 7 and Vista you have to format it in GUID Partition Tables (GPT) to use the entire 3TB as storage.
    For Windows XP you need a special driver to use the entire 3TB.

    http://seagate.custkb.com/seagate/crm/selfservice/search.jsp?DocId=218619 
    http://www.ghacks.net/2010/11/04/how-to-use-3tb-hard-drives-on-windows-xp/