External NTFS disks not recognized on Win11

Operating Systems & Open Source Windows
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Hi,

I am currently supporting an older friend to migrate Win7 to Windows 11. He has a bunch of external 3.5" disks (NTFS) that he uses with an external enclosure. Most of the disks work as expected, but some simply don’t show a partition. I could reformat them, but this is not the goal.

If the enclosure is plugged into the old computer everything works as expected.
Since most of the disks still “work” and show up properly on Windows 11 I am puzzled what the root cause might be.

I think we can rule out:

  • Faulty driver for external enclosure as most disks work
  • Faulty drives as they show up with the correct paritions on Win7

Trying to get information about such a problem, the only solution I was able to find was a reformat with re-adding data from backups. But since those are TB disks I am not keen on going that root (Besides, there is something off …)

Any ideas or tools to “recover” the partition information for W11 ?

Thx

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Win 11 might expect that a large external disk has its layout specified in newer GPT format, while this disk may have its layout specified in MBR format.

Can you confirm that the partition layout is specified in the older MBR format, not the newer GPT format? (I don’t recall the Windows tools like diskpart and chkdsk to do this.)

You most likely will be able to add the GPT data at the start of the disk – it says ‘this has an NTFS partition starting at one address and ending at another address’ – and Win11 will pick it up. However, there’s a chance that the partition begins before there’s space for the GPT in its conventional location. Backup the disk to a spare space, recreate as GPT format, and restore the data. I think it’s a good idea to backup this data any way before messing with it, no?

K3n.

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I can (sort of) understand if Windows 11 will not create an MBR partition on a large enough disk. But refusing to read it sounds simply stupid.

Be that as it may, if that is indeed the case, the following might be helpful:

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They were GPT, but it was safer to buy a pair of new ones and rebackup stuff. Now I can format the old ones and repurpose.

Nevertheless, strange thing …

Thx for the replies.

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Have you tried looking at them through the Disk Management console? (diskmgmt.msc) if you see the partitions there, you may be able to force mount them.

I helped my brother to migrate from Windows 7 to Windows 10 around 6 years ago and found out that the partitions were not mounting automatically, but all of them were in working order.

Edit: to “force mount” them, right click on a partition and select the option to assign it a drive letter.