Chosen Solution
Recently I replaced the 1 TB hard drive with a 1 TB SSD and forgot to split the fusion drive. Since I already paired the old SSD to the new SSD I cant simply reconnect the old drive. I plugged the old hard drive into another computer i have and the drive wont mount. Is there anyway to get the data off the hard drive?
First setting up a dual SSD Fusion Drive really doesn’t improve performance! Depending on the size of the blade SSD its best to just setup a dual drive config with the blade SSD setup as the OS and App drive. If you have a small Fusion Drive SSD (128 GB or smaller) then its best just to leave it unused. As far as recovering your files from the original HDD if you’ve installed anything higher than High Sierra (likely here) then your drive is setup with APFS file system so older HFS+ drive & file recovery tools are useless! Apple has not offered the drive/file recovery folks the means to recover drives or files under APFS. As you’ve over written the cache drive (blade SSD) the keys are gone!
