Mac First Aid Issues When using External Hard drive

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Level 1

4 points

Mac First Aid Issues When using External Hard drive

Hello, We used Mac first aid on an external hard drive and it actually shrunk the file size of the drives. The file type are MXF video files. Here are the details:

-We were able to access OCM that were tagged as problematic. Two problematic OCM files’ video did cut out before the metadata’s listed end run time.

-It appears while the XML metadata files are fine for the observed problem OCM, the MXF files are corrupt.

-In addition to ending before their total run time listed in the metadata, the files had a smaller data size that uncorrupted files the similar length.

It is suspected that the original camera master MXF video files and metadata XML files had been separated, breaking their OCM file structure, and rendering them unplayable.

Have you seen this before and can you recommend a resource to fix? Thanks!

Posted on Nov 7, 2025 7:16 AM

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Answer 1

Nov 10, 2025 6:49 AM in response to Mac_MKC

Mac_MKC wrote:

Hi Allen, It was a Seagate Exos Enterprise 24TB.

There are a lot of pieces to this puzzle.

Can you put ~23 TB of data onto the device? Counterfeit devices and counterfeit capacities are unfortunately all too common. (This can be subtle too, as unique data needs to be written in totality and avoiding any potential compression support or just-drop-the-zeroed sectors support, and only then verified for correctness.)

Which volume format? ExFAT? NTFS with third-party NTFS? HFS extended? APFS?

How is the HDD connected? USB4? Is the external storage an array configured for RAID? (potential wrinkles)

Are the files and the volume structure and metadata all verified as valid before the First Aid pass?

Do the Seagate HDD diagnostics show any issues?

Does DriveDx report any issues?

Are the files corruptions independent of the storage involved, and tied to (for instance) ExFAT support on the source, or (for instance) file corruptions arising at the source?

Camera firmware current?

HDD firmware current?

That’s a lot of words to indicate you’re going to have to troubleshoot this, and figure out where the error is arising. Whether this is arising from the camera, from the volume format support either camera source or macOS destination, from firmware issues on the camera or HDD, from bugs in the macOS file system support, from bugs in the storage array hardware, from macOS Disk Utility, or from some other source. Or maybe the camera wrote bad data in the file, or created a bad volume structure, which can happen. Sometimes firmware surprises and firmware settings surprises await, too. Or a bad cable somewhere.

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Answer 2

Allan Jones

Level 9

77,750 points

Nov 8, 2025 6:20 PM in response to Mac_MKC

We used Mac first aid on an external hard drive and it actually shrunk the file size of the drives.'

What brand and mode is the external. We see a lot of reports of issues with the scammy low-cost large capacity external SSD flash drives doing odd things when reformatted.

Do a search for "fake large capacityr ssd" and look as the many fraud reports.

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Answer 3

Mac_MKC Author

Level 1

4 points

Nov 10, 2025 6:14 AM in response to Allan Jones

Hi Allen, It was a Seagate Exos Enterprise 24TB.

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