4TB external disk is shown as MBR formatted. How is this possible?


  1. Fortitude
    Posts : 184
    Windows 11 Pro
       New #1

    4TB external disk is shown as MBR formatted. How is this possible?


    The reason for my question is as follows.

    I had a 4TB Samsung D3 Station external disk that suddenly stopped working. I determined that the problem must have been with the external enclosure and I therefore bought a replacement. Upon trying to connect the drive Hard Disk Sentinel reported that "the partition on this hard disk created (sic) with 4K physical sector size but the current physical sector size is 512 bytes" and "it is recommended to re-connect the hard disk as previously connected (probably with different USB adapter, enclosure, docking station or so to access the partition with ll stored data - otherwise data loss may occur".

    To cut a long story short, I eventually reformatted it as the data on it were already backed up elsewhere. However, I ended up with two partitions and I couldn't merge them, apparently because the size of one of them exceeded 2 TB. I finally used a program from AMOEI and I created a single partition on the disk, equal to nearly 4 TB.

    The partition now is GPT type. However, the previous partition on this disk, also 4 TB, was type "Basic MBR". So how come it was 4 TB Basic MBR in its original (new) form whereas I was restricted to partitions below 2 TB later on when I wanted to have a single MBR type disk up to 4TB? Does it have anything to do with the enclosure, that is the original enclosure from Samsung compared to the new enclosure that I bought?
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  3. jumanji
    Posts : 11,627
    Windows11 Home 64bit v:23H2 b:22631.3374
       New #2

    Yes, your good old 4TB Samsung D3 Station external disk was an advance formatted MBR drive.

    A normal MBR disk can address only 4,294,967,295 physical sectors. The normal sector size is 512 bytes. That works out to 4,294,967,295 sectors ( that can be addressed) * 512 bytes/sectors = 2,199,023,255,040 bytes or 2.2TB.

    To make larger than 2TB drives compatible with Windows XP, ( Windows XP is GPT blind and GPT came much later than large capacity drives) eight 512 bytes physical sectors were combined into one 4096 bytes per sector ( logical sector size). That way MBR could address 2.2TB*8 = 17.6TB drives. (    4,294,967,295 sectors ( that can be addressed) * 4096 bytes/sectors = 17,592,186,040,320 bytes or 17.6TB).

    The SATA to USB bridge in those advance formatted drives consists of a special Drive Translation Circuitry which takes in eight of the usual 512 byte data stream - with the clock/synchronising bits at the beginning and end - combines it and converts it into a 4096 byte stream ( shifting the clock/synchronising bits to the beginning and end of the 4096 byte) and writes into the 4096 bytes per sector. While reading the drive the same circuit breaks the data coming from the 4096 bytes in each logical sector , and presents it as a 512 bytes /sector data to the OS.

    When you put the HDD into a new case, the drive translation circuitry is absent in the SATA to USB bridge in it and the drive is seen in its original 512 bytes/sector size. You can only see 2TB if you initialise and format it as an MBR drive.. Rest of the space will be inaccessible. Initialise it as a GPT drive and format it, you can see and use the full capacity.

    We had a few cases requiring data recovery on the HDD taken out from such cases, and we had used TestDisk to read the HDD as a 4096 byte/sector size and recover the data. ( software Drive Translation :))

    One such successful recovery here after changing the sector size from 512 to 4096: Hard Drive seems corrupt. 1 Partition now showing as 3 Partitions?
    Last edited by jumanji; 10 May 2018 at 22:53.
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  4. Fortitude
    Posts : 184
    Windows 11 Pro
    Thread Starter
       New #3

    Thank you very much for the explanation!
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  6. jumanji
    Posts : 11,627
    Windows11 Home 64bit v:23H2 b:22631.3374
       New #4

    Most welcome.
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  7. XP Sentimental
    Posts : 2
    Windows 10, XP Pro 32
       New #5

    Samsung D3 Station readable on XP system


    B"H

    Terrific explanation of the trick that Samsung D3 Station to allow 2+ terrabyte drives to work on XP! Thanks for that!

    The original Samsung D3 Station enclosures were sold with 2-6 terrabyte drives.

    Is there a way to use the D3 Station enclosure to format larger drives, (say 8 terrabytes or larger).

    I tried putting an 8 TB drive into the D3 Station enclosure, made it MBR in windows 10. Then tried to format it as NTFS in windows 10, but that didn't work.

    Does the D3 Station enclosure work with specific drives only? Is there a workaround?

    TIA!
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  8. jimbo45
    Posts : 11,247
    Windows / Linux : Arch Linux
       New #6

    XP Sentimental said:
    B"H

    Terrific explanation of the trick that Samsung D3 Station to allow 2+ terrabyte drives to work on XP! Thanks for that!

    The original Samsung D3 Station enclosures were sold with 2-6 terrabyte drives.

    Is there a way to use the D3 Station enclosure to format larger drives, (say 8 terrabytes or larger).

    I tried putting an 8 TB drive into the D3 Station enclosure, made it MBR in windows 10. Then tried to format it as NTFS in windows 10, but that didn't work.

    Does the D3 Station enclosure work with specific drives only? Is there a workaround?

    TIA!
    Hi there
    @XP Sentimental

    @jumanji

    Even simpler method

    I don't have a physical XP system any more but it runs perfectly as a VM.

    Attach as a network shared drive !! Here I've a music folder on an HDD that's > 2TB and the whole drive is accessible (18 TB).

    4TB external disk is shown as MBR formatted. How is this possible?-xplan.png

    Also for a single or even 2 drives simply use a SATA-> USB attached 1 or 2 bay "HDD" enclosure - these have their own power etc and can easily work with modern 20 TB drives and are cheap !! --remember for XP there's no USB3 drivers - so if using a VM for direct attachment to the VM ensure the USB settings in the VM configuration file are for USB 2. If you use a VM and connect the enclosure to the HOST machine you can use USB3 and still set these up as network shared drives. Enable though SMB1 on a Windows Host machine.

    Cheers
    jimbo
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  9. XP Sentimental
    Posts : 2
    Windows 10, XP Pro 32
       New #7

    We are using an actual xp systems..... not virtual machine, vm.

    We do have several D3 Station enclosures looking for a tenant.....

    Any suggestions how to accomplish reading the larger drives as standalone computer with the D3 Station without vm?
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  10. Megahertz
    Posts : 6,293
    Windows 11 Pro - Windows 7 HP - Lubuntu
       New #8

    XP Sentimental said:
    B"H

    Terrific explanation of the trick that Samsung D3 Station to allow 2+ terrabyte drives to work on XP! Thanks for that!

    The original Samsung D3 Station enclosures were sold with 2-6 terrabyte drives.

    Is there a way to use the D3 Station enclosure to format larger drives, (say 8 terrabytes or larger).

    I tried putting an 8 TB drive into the D3 Station enclosure, made it MBR in windows 10. Then tried to format it as NTFS in windows 10, but that didn't work.

    Does the D3 Station enclosure work with specific drives only? Is there a workaround?

    TIA!
    How many bytes per sector does the 8 TB drive have?
    Advanced Format - Wikipedia
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