A second partition disappeared after setting up Time Machine

[fstigre]

I have been using a 2 GB Hitachi external hard drive with two partitions for a couple of years now. The drive has a 1TB partition for saving general files and another 1TB partition for Time Machine. I have been using Time Machine with an Intel iMac for about a year or so, and today I decided to reformat the Time Machine partition to be able to use it with an M1 iMac, here is what I did.

1. Reformatted the Time Machine partition: No problems here, the reformat process when well at this point I ended up with the same partitions I previously had.

2. Setup Time Machine: Right after the reformat, I started setting up Time Machine in my M1 iMac, when I selected the Time Machine partition I was asked to enter a password for encryption purposes so, I did enter a password and continued with the Time Machine process. After a very short waiting, I ended up with only the Time Machine partition with the whole 2TB allocated to it, I'm not sure why the other partition was merged after the encryption process finished.

Any idea why my second partition disappeared/merged after Time Machine encrypted the Time Machine partition?

Has anyone seen this before?

Is there anything I can do at this point?

My biggest issue here is that I had a lot of photos in my other partition.

Thanks a lot.

 

[leman]

I am afraid you might have accidentally reformatted the entire disk rather than the single partition... sorry... I assume you don't have the backups for the photos? Never perform live low-level manipulation on a disk that you are afraid to lose!

 

[fwmireault]

I don't know exactly what happened in your case, but I recommend you find a good software to recover your files. Some of them may be corrupted, but something like Disk Drill works pretty well and will give you back most of your lost data.

I have the exact same setup than you, a 2TB external drive with half for Time Machine, and half for other files. I recommend in your settings that you add this other partition to your Time Machine backup. It will take more space for sure, but it will give you an extra protection against unwanted data loss

 

[w5jck]

I recently bought a MacBook Air M1 and set up a 4TB HDD for TimeMachine with 2TB for TM and 2TB for other data storage. As I recall, there was a note in the Apple instructions warning that if you reformatted the HDD drive for TM, the entire HDD would be reformatted. I'm old and my memory isn't as good as it was decades ago, but I do remember reading something like that warning. I didn't pay much attention to it though as I was using a brand new HDD that needed to be reformatted anyway. I find that with Apple instructions you really need to carefully read all the fine print. They are not always up front with all the important details...

 

[fstigre]

Thank you all very much for your input.

 

[NoBoMac]

What @w5jck said.

My memory is not great either, but recall basically what they said. Erases everything and creates a new APFS formatted drive.

Additionally, if you start off with an APFS drive and turn on encryption in Time Machine, TM will reformat the drive and create an APFS volume with a role of "Time Machine, encrypted". That one ticked me off: "I've already formatted and encrypted! Why do you keep re-formatting?!?!?!?".

 

[fstigre]

What @w5jck said.

My memory is not great either, but recall basically what they said. Erases everything and creates a new APFS formatted drive.

Additionally, if you start off with an APFS drive and turn on encryption in Time Machine, TM will reformat the drive and create an APFS volume with a role of "Time Machine, encrypted". That one ticked me off: "I've already formatted and encrypted! Why do you keep re-formatting?!?!?!?".

That was my case, since I have had reformatted the partition I thought that Time Machine was going to use the partition as it was without reformatting, but as you guys pointed out, Time Machine apparently needs to occupy the whole hard drive regardless what partitions you already have, that's probably why it reformats the drive.