I had an external hard drive with two partitions (Thing1, Thing2). Thing1 contained manual file backup data and Thing2 was empty and was my targeted drive for Time Machine.
I opened Time Machine and selected Thing2 as the disk for Time Machine to use. Time Machine warned that it was about to format the drive/partition (to which I consented).
I then immediately performed a backup of my Macintosh HD.
After the backup concluded, I noticed that Thing1 was no longer mounted. I rebooted and Thing1 still didn't mount.
When I open Disk Utility, I see the following for my external drive.
I do not know (cannot recall) what the original partition format of Thing1 was. It would not surprise me if it were a partition format that would be accessible from multiple platforms.
I have not performed any action on the disk (other than inspection) after completing the backup. Thing1 appears to be missing and contains important data that I need to recover. I have spent some time looking for information on what actions Time Machine takes when initializing the drive and for examples of others who have experienced my same mistake. So far no luck so I'm reaching out to your collective knowledge.
It is my hope that the partition table was damaged and that precision actions can make the data accessible again.
I am running macOS Sierra 10.12.3 (16D32).
How can I determine if my original data on Thing1 is recoverable?