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External hard drive is mounted as read only

How do I fix my external drive that is labeled 'read only' in disk utility?

Last week my computer while in use said that it could not repair a Photos library located on my 8 TB external drive formatted as a Raid 1 setup. This lead to me finding that the entire drive is marked 'read only'.

I have tried First Aid which results in the error code -69845 and -69842

I have also tried changing permissions in Finder and Recovery Mode to no avail.

I have also selected the Photos Library and attempted to move it onto my internal drive which then said it was 'read only'. And mounting the external drive in another Mac comes up with the same issue.

I cannot reformat this drive as it contains sensitive files that are too large to be moved onto a separate device. Is there any way to find out what happened?

Posted on Oct 31, 2022 9:39 AM

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3Design Author

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Posted on Nov 8, 2022 2:33 PM

8Tb External Hard Drive is mounted ‘Read Only’

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Barney-15E

Level 10

122,300 points

Nov 3, 2022 12:37 PM in response to 3Design

Everyone is really “others” which are users on that Mac who are neither the owner nor a member of the same group as the drive. Everyone doesn’t include you since you are the owner.

Barney-15E

Level 10

122,300 points

Nov 3, 2022 12:39 PM in response to 3Design

Did you ever try to copy the Library to somewhere within your home folder or /Users/Shared?

Barney-15E

Level 10

122,300 points

Nov 4, 2022 6:04 PM in response to 3Design

So, you haven’t tried copying your photos library to a user-writeable location on your internal drive? You originally stated you couldn’t copy it to your startup drive.

Barney-15E

Level 10

122,300 points

Nov 8, 2022 5:10 AM in response to 3Design

The OS will prevent you from trying to modify a startup drive or a Time Machine drive. Was it ever used for Time Machine?

3Design Author

Level 1

4 points

Nov 8, 2022 12:20 PM in response to Barney-15E

No I have a smaller external drive established for that.

Would EtreCheck help to give you a better overview?

Barney-15E

Level 10

122,300 points

Nov 14, 2022 12:47 PM in response to 3Design

I can't seem to open your Additional text submission. It starts to reload the page, then times out with a server failure.

Perhaps try posting again.

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External hard drive is mounted as read only