Cannot mount fusion drive from failed iMac

[MarcoPolansky]

I had a 2017 27inch, 5k iMac. The logic board failed so I removed the 3tb HDD portion of the fusion drive, put it in an external enclosure and connected it to a new iMac for the purpose of data recovery.

The problem is, the drive will not mount on the new iMac. It shows up fine in disk utility as "disk3" but when I try to mount the physical portion "disk3s2 3TB Apple_AFPS" I receive the error "com.apple.DiskManagement.disenter error -119930868"

Running first aid on "disk3" says "The partition map appears to be OK", but I am unable to run first aid on "disk3s2" since it will not mount.

I was told that after the Mojave update, the only drive you need for data recovery is the HDD since the SSD simply serves as a cache for frequently used files. Both the old iMac and the new iMac were running on Monterey

Erasing and reformating the drive is not an option, as it contains family photos which I had not backed up (I know, lesson learned)


Thanks in advance for any help!

 

[chrfr]

I had a 2017 27inch, 5k iMac. The logic board failed so I removed the 3tb HDD portion of the fusion drive, put it in an external enclosure and connected it to a new iMac for the purpose of data recovery.

The Fusion Drive consists of the 3TB drive you have as well as the SSD that’s in the computer. You do need both disks to recover your files.

 

[Fishrrman]

Agree with what chrfr posted above.

The fusion drive is TWO drives, "melded together" by software.
Unless you have both of them, and both running "as a fusion drive", what is on EITHER ONE of those drives is UNRECOVERABLE.

I'm wondering if even a data recovery firm could get the data off only "one component" of the fusion drive.

Do you still have the iMac?
Do you still have the SSD portion of the fusion drive?

If you want that data back, what you need to do is:
- put the drive back into the iMac it came out of
- get the iMac functioning again
- get the fusion drive mounted and get your data from it.

If you can't do this yourself, it's possible that a data recovery outfit that specializes in Macs MIGHT be able to put the SSD and the HDD into an iMac, get it working again, and get the data that way.
But it's going to cost you A LOT of money.

The predicament you face now is why we have a concept called "backing up".
Next time, I suggest you learn about it and ... do it.

 

[MarcoPolansky]

Thank you both for your replies!

Your version of a fusion drive was correct, up until 2018, when macOS Mojave was released. At this point, the blade SSD part of the "fusion drive" was converted into a CACHE drive only. Containing 100% duplicate data from the main HDD. At this point the HDD was supposed to be "plug and play" capable in other mac devices. Apple said they wouldn't even need the SSD for data recovery on their end, and to just bring in the HDD.

Even with basic data recovery software I was able to recovery 98% of the files off the drive with no problem (It's the other 2% I'm interested in, as well as the file names)

I'm mostly interested in what could be preventing the drive from mounting properly on my machine.

 

[Fishrrman]

"Even with basic data recovery software I was able to recovery 98% of the files off the drive with no problem (It's the other 2% I'm interested in, as well as the file names)"

Good that you got that much back. I'm amazed it worked at all.
It's probably not worth spending much money for "the other 2 percent".

Re file names:
One of the realities of data recovery is that you often lose file names and folder hierarchies with the "recovered" data.
This is because file names and folder hierarchies exist in the "drive directory", which may be corrupted or not there at all.

The data recovery software "skips around" directory information, and goes "directly to the platters", scavenging each block, and trying to re-assemble what it finds.

Chances are you're going to have to examine each file individually, and then rename each one "by hand". Yes, I realize this could take quite a bit of time. The consolation is, "you got the data back".

If some of the files are mp3 files, or in other audio formats, here's a trick to try:
Create a new library using iTunes, then "dump" all the un-named files into it.
iTunes may be able to read the metadata of the files, and show you the names.
(You will still have to rename the files, however -- but at least you'll know what they are).

 

[mj_]

Your version of a fusion drive was correct, up until 2018, when macOS Mojave was released. At this point, the blade SSD part of the "fusion drive" was converted into a CACHE drive only. Containing 100% duplicate data from the main HDD. At this point the HDD was supposed to be "plug and play" capable in other mac devices. Apple said they wouldn't even need the SSD for data recovery on their end, and to just bring in the HDD.

Where did you get that information from? I have never heard or read this before.