Old Macintosh HD not recognized by iMac

[TheGuru]

Hello folks!
This is my 1st post in this forum and would like some assistance.
Apple had replaced a 3TB HD on my iMac and I currently have plugged in the old HD into a USB 3.0 enclosure which is Mac compatible. The issue is iMac recognizes the External hard drive as 'Macintosh HD' but I am not able to view the content on the HD.

This is the error I am seeing when I click on the HD in Disk Utility program

"This Fusion Drive is missing a disk. Would you like to rebuild this Fusion Drive?"

Any suggestion how I can view data on this HD or do I need to Rebuild the disk which will erase all the data on the drive.

Thank you.

 

[matreya]

Well, normally, people would already have all their data backed up to at least a time machine backup...

I've come across some command-line voodoo that purports to fix a fusion volume, but I would be very wary of following them.

I also wouldn't trust re-using a defective drive, a new one is a better investment.

 

[Fishrrman]

We need more information.

You wrote above:
"Apple had replaced a 3TB HD on my iMac"

Did you buy the iMac with a fusion drive as standard equipment?
Did you subsequently experience a drive failure?
Did they put a -fresh- 3tb hard drive into the iMac, and then give you the old drive back?

I'm thinking that if the iMac came originally with a 3tb fusion drive (which is composed of a 128gb SSD and a 3tb HDD), and if Apple replaced the 3tb HDD, and if "the old one" is what you now "have in your hand" -- that Disk Utility is still "seeing it" as representing "one-half" of a fusion drive and will try to "re-integrate" it with other drives in your Mac.

If that's the case, you DON'T want Disk Utility to "rebuild the fusion drive".
You may already have a working fusion drive setup -in- the iMac.

Again, we need more information.

Instead, you want to re-initialize the 3tb "drive in your hand" to HFS+ and use it as a "standalone" drive...