Running first aid on an external disk results in errors that cannot be fixed even in recovery mode in OS Sierra?

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Level 1

9 points

Running first aid on an external disk results in errors that cannot be fixed even in recovery mode in OS Sierra?

I am working in OS Sierra and recently tried to open a .tar archive file I had on an external hard drive. It stated that there was an input output error and so immediately I suspected there may have been corruption in the drive because I had received an error while tried to create a .tar file earlier.

I ran disk utility on the external hard drive, then it stated that "First aid found corruption that needs to be repaired. To repair the startup volume, run First Aid from Recovery."

I went into recovery mode by pressing command R on startup, and tried to run First Aid again on the disk, but got the same message. Digging deeper, it states:

"Problems were found with the partition map which might prevent booting"

It seems that I cannot repair the disk and get the same message even after going into the Recovery Tools on startup. What can I do here? Here is a picture I get both in Sierra's disk utility and on Recovery Tools on startup.

MacBook Pro (Retina, 13-inch, Mid 2014), iOS 8.1.2

Posted on Aug 25, 2017 6:41 PM

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Answer 1

John Galt

Level 10

141,144 points

Aug 25, 2017 6:57 PM in response to proconverter

It's not a problem unless you intend to boot from that volume. Even then it still might not be a problem.

Fixing the partition map will require erasing it. However...

It stated that there was an input output error and so immediately I suspected there may have been corruption in the drive because I had received an error while tried to create a .tar file earlier.

That's correct. I/O errors indicate that disk should no longer be considered reliable. You can erase the disk but those errors will become more frequent until it's essentially unusable. That is probably the reason the partition map became corrupted in the first place.

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Answer 2

proconverter Author

Level 1

9 points

Aug 25, 2017 7:05 PM in response to John Galt

Thanks for the reply. The errors didn't seem to occur until I unplugged the drive (NTFS format using Paragon to read it) without properly ejecting it. Are you saying that there are physical problems that exist that a complete reformat will not be able to solve? In other words, should I just throw the drive away?

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Answer 3

John Galt

Level 10

141,144 points

Aug 25, 2017 7:43 PM in response to proconverter

(NTFS format using Paragon to read it)

That is an important little detail. A sudden power interruption cannot corrupt Mac HFS+ formatted volumes, but I have no idea what that would do to an NTFS formatted volume. If that error occurred on a Mac journaled volume it would imply a physical problem. NTFS, who knows.

It's probably fixable by reformatting it, unless you know of a Windows PC utility that can fix a corrupted partition map without erasing it.

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Answer 4

dialabrain

Level 10

122,549 points

Aug 25, 2017 7:43 PM in response to proconverter

proconverter wrote:

Thanks for the reply. The errors didn't seem to occur until I unplugged the drive (NTFS format using Paragon to read it) without properly ejecting it. Are you saying that there are physical problems that exist that a complete reformat will not be able to solve? In other words, should I just throw the drive away?

FWIW, I don't believe Paragon would load while in recovery mode so First Aid would not be able to write to the drive in order to fix it.

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