Disk utility First Aid deleted 2.2TB from my 4TB external HDD

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Level 1

8 points

Disk utility First Aid deleted 2.2TB from my 4TB external HDD

Hi,

Just like title says, I ran First Aid using Disk Utility on my external HDD (4TB capacity). 2.2TB were used out of the 4TB and after the Disk Utility run, the used space simply is not accessible anymore. Basically the HDD shows only 1.8 TB capacity(the remaining space) out of the 4, like the rest of 2.2 TB never existed in the first place. Very strange and I cannot access any of my data.

Has anyone experienced something like this before ? Is there a solution? I checked myself some alternatives, but nothing seems to work.

I have macOs Catalina on a mac mini 2014.

Thank you in advanced for any solution you might have.

Posted on Oct 31, 2020 1:36 PM

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Answer 1

HWTech

Level 9

68,792 points

Oct 31, 2020 5:44 PM in response to Inferno33

It means you are using an older model USB to SATA Adapter, dock, or enclosure for the external drive that doesn't work with a drive over 2TB in size. Purchase a newer USB to SATA Adapter, dock, or enclosure which supports a 4TB drive.

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Answer 2

Meg The Dog

Level 6

13,820 points

Oct 31, 2020 2:35 PM in response to Inferno33

What was the reason you ran Disk Utility First Aid on the disk?

How is the external disk formatted?

Can you post a screenshot of the sidebar in Disk Utility with the sidebar view set to Show All Devices?

MtD

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Answer 3

HWTech

Level 9

68,792 points

Nov 1, 2020 9:25 AM in response to Inferno33

While clicking on the physical drive as in your last screenshot you can click the "Partition" button to add a second partition to the drive to use the rest of the drive. I don't recommend this option since sooner or later you will want to erase the whole drive to have a single partition. Better to do it now with just 2TB of data on the drive than with 4TB of data.

FYI, you should have a backup of your external drive if it contains important & unique data.

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Answer 4

Inferno33 Author

Level 1

8 points

Oct 31, 2020 3:55 PM in response to Meg The Dog

I have attached 2 screenshots. You can see that although Disk utility sees the normal size of the external HDD to be 4TB out of which 2.2 TB are used with my files, actually 1.8TB are actually seen as the full capacity of the HDD and that's not correct.

The disk is has the MS-DOS(FAT32) format. I am running First Aid from time to time on the HDD to check if there are any errors. I have never had any issues with this drive until now and I have been having it for like 1 year already. I was able to access my files from both windows 10 and macOs.

Is there any way I can fix this ? Is there any way I can retrieve my 2.2 TB of data ?

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Answer 5

Inferno33 Author

Level 1

8 points

Oct 31, 2020 6:13 PM in response to HWTech

Hi HWTech,

Thank you for your input, but are you certain the Adapter is the issue here? I had no problems with it until I ran First Aid with Disk Utility like 2-3 days ago and the USB to SATA Adapter is the original one which came in the box when I bought the HDD.

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Answer 6

Inferno33 Author

Level 1

8 points

Nov 1, 2020 5:00 AM in response to HWTech

I am attaching a new screenshot now with the "Show all Devices" option selected. The Fat32 format system was used from the very beginning and I was able to see everything, the problem started after I ran a First Aid. I am inclined to say it is a Software error though or an update, but even so, what type of adapter is best to connect 4TB external drives ?

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Answer 7

Eau Rouge

Level 8

42,656 points

Nov 1, 2020 8:19 AM in response to HWTech

" Just make sure to use Disk Utility to erase the drive as GUID partition and exFAT so that both Windows and macOS can access the drive."

Thought exFAT had to be on a Master Boot Record partition.

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Answer 8

Inferno33 Author

Level 1

8 points

Nov 1, 2020 8:37 AM in response to HWTech

I am attaching a new screenshot. I hope this one is the one you need.

I am assuming there is no way for me to format the drive without losing my used 2.2TB unfortunately, right ?

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Answer 9

HWTech

Level 9

68,792 points

Oct 31, 2020 6:32 PM in response to Inferno33

I just noticed in your screenshot that you are using FAT32. The FAT32 file system can only support up to 2TB. Also Disk Utility defaults to a "volume" view now. To show the physical drive on the left pane of Disk Utility you need to click on "View" and select "Show All Devices". I cannot currently tell if the "WinInstall" partition is part of your 4TB drive or not.

I know that the 1.8TB size is what gets reported when using an adapter that isn't made to work with a drive larger than 2TB. Maybe the adapter is defective. Surprisingly after all these years vendors still making & selling devices that do not work with drives larger than 2TB. Make sure to show the physical drives in Disk Utility to see how the drive is partitioned.

Did this adapter ship inside the drive box or was it bundled externally? If it was inside the main packaging, then you should contact the manufacturer for assistance.

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Answer 10

HWTech

Level 9

68,792 points

Nov 1, 2020 8:17 AM in response to Inferno33

Select the physical drive in Disk Utility since I already know about the the "My HDD" volume.

FAT32 has a 2TB drive size limit:

https://www.makeuseof.com/tag/format-large-hard-drive-fat-fat32/

Why are you using FAT32 anyway since it has file size restrictions of 4GB as well? FAT32 should only be used on USB sticks and special system partitions.

If you need to share a drive with Windows, then you should be using exFAT. Just make sure to use Disk Utility to erase the drive as GUID partition and exFAT so that both Windows and macOS can access the drive.

If you are only using this drive with macOS, then the drive should be erased as GUID partition and MacOS Extended (Journaled).

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Answer 11

HWTech

Level 9

68,792 points

Nov 1, 2020 8:35 AM in response to Eau Rouge

Not that I'm aware of. MBR cannot handle 4TB drives which is why GPT (or GUID) partitioning was created. MBR has a 2TB drive limitation:

https://docs.microsoft.com/en-us/troubleshoot/windows-server/backup-and-storage/support-for-hard-disks-exceeding-2-tb

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Disk utility First Aid deleted 2.2TB from my 4TB external HDD

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