Chosen Solution
The iMac itself seems nonrecoverable, no matter what I do I cannot get it to even boot anything. As such I want to recover the data on the Fusion Drive using a non-Apple computer. The HDD component is no problem, but I understand Apple’s been using proprietary connectors for their SSDs some time now. It looks like SATA M.2 but it isn’t, it’s the 7+17 pins connector from below image:
I’m pretty sure the drives are still good; for the HDD I ran a SMART check as well as both short and long self tests and everything was reported as fine. Even the SMART attributes don’t show a lot of wear, and I can’t imagine the SSD being used more excessively than the HDD (relatively speaking, due to size differences). I have already tried just mounting the HDD from a Linux-based rescue distro, since I figure most important data would be on the HDD anyways. But apparently all metadata is saved on the SSD, so without it you can’t see the original filesystem structure, making recovery pretty much impossible. I’m looking for a way to stick the SSD in my recovery rig so that I can mount it together with the HDD. It only supports good ol’ SATA, but I do have an adapter for both mSATA and actual M.2 to plain SATA. So even something for converting the Apple connector to mSATA would work, as I think everything in the chain still speaks the SATA protocol. It would “simply” be a conversion at the physical/electrical level so there shouldn’t be any noticeable performance loss. I’ve checked out various adapters but they all convert to the Apple connector, which is the opposite of what I need.
Wow we are taking a very big left turn here! First your apps and data won’t be accessible to your ‘other’ PC. You require a Mac to run the Apps and access the data as macOS is not compatible with Windows or Linux or anything else! The second issue is the file system was upgraded from HFS+ to APFS some where along the line if you are running anything newer from Mojave onward. This also makes it even harder as only Mac’s can access APFS file system (you could get a driver for Windows to read HFS+, but only a limited number of file types like MS Word) OK, your blade SSD is not important from a data perspective! Your data is strictly on the HDD, the SSD is used as a cache drive holding a duplicate of the more accessed data (like your OS files). As long as you shut your system down cleanly you won’t have any data lost. I would encourage you on getting another Mac system making data recovery easier.
