I have a new 4TB external HDD and a non-UEFI BIOS. MBR or GPT?


  1. Posts : 6
    windows 10
       #1

    I have a new 4TB external HDD and a non-UEFI BIOS. MBR or GPT?


    I plugged my new, empty Western Digital 4TB external drive into my old PC, and it is a MBR HDD. The PC is too old to have UEFI. I want the drive to be as reliable as possible and to work on my new (UEFI) PC as well. Should I convert it to GPT now?
    Both PCs are on Windows 10.
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  2. Posts : 5,478
    2004
       #2

    I don't think GPT is really more reliable than MBR and either of your PCs could access either.

    I think I'd convert it GPT though if it is still empty - you might decide you want more than 4 partitions in the future and this is easier with GPT. You can always change MBR to GPT later using partition management software but it is probably easier to do it now.
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  3. Posts : 2,799
    Linux Mint 20.1 Win10Prox64
       #3

    MBR only supports 2TB max. You must initialize with GPT to use all 4TB
      My Computer


  4. Posts : 11,247
    Windows / Linux : Arch Linux
       #4

    Hi there

    You can't BOOT from this drive on MBR but you can use the whole 4TB if you use it as a NON boot device and convert to GPT.

    Use another drive or an SSD as MBR to boot from.

    Cheers
    jimbo
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  5. Posts : 2,935
    Windows 10 Home x64
       #5

    Can't you boot on MBR even if you make several smaller partitions?
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  6. Posts : 6
    windows 10
    Thread Starter
       #6

    topgundcp said:
    MBR only supports 2TB max. You must initialize with GPT to use all 4TB
    This is the common wisdom, but untrue. Western Digital ships new 4TB external drives initialised to MBR. I'm not mistaken. I checked three different ways to see it was MBR.
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  7. Posts : 5,478
    2004
       #7

    ontodva said:
    This is the common wisdom, but untrue. Western Digital ships new 4TB external drives initialised to MBR. I'm not mistaken. I checked three different ways to see it was MBR.
    Must have 4k sector size (you can check the bytes per sector with fsutil fsinfo ntfsinfo x: ) so the limit for MBR is 8 times bigger ~16TB. I'd reformat it GPT based on this though..

    The manufacturer is taking advantage of the fact that this is an external hard drive, with an assumption that it will only be used for storage and not booting. However, this creates another set of compatibility problems, where programs that rely on 512-byte sector sizes may not work correctly:

    Partitioning tools that do not support 4Kn drives will not function correctly with this drive.
    Some database programs use direct disk I/O for performance and data integrity. These programs will not function correctly if they are not designed to handle 4K sectors.
    windows 8.1 - How can a MBR formatted hard drive exceed 1.81 TiB capacity? - Super User
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  8. Posts : 6
    windows 10
    Thread Starter
       #8

    lx07 said:
    Must have 4k sector size (you can check the bytes per sector with fsutil fsinfo ntfsinfo x: ) so the limit for MBR is 8 times bigger ~16TB. I'd reformat it GPT based on this though..

    windows 8.1 - How can a MBR formatted hard drive exceed 1.81 TiB capacity? - Super User
    That is absolutely the clincher. GPT it is.
    Thanks.
      My Computer


 

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