M1 MacMini External Time Machine Hard Drive Continues to Run?

[jazz1]

I have an OWC external HD that I turn on once a week to back up my M1 MacMini. I notice after the backup is complete the computer continues to run the HD. Can I assume this is normal. Is TimeMachine "thinning" out the old data? Is Time Machine re-encrypting the data? Note I have to enter a password to get the external HD to mount.

Maybe I should just let the external HD run all the time. But it is in my bedroom, and I was trying to avoid the HD running noise while I was sleeping. I probably should have just gotten an SSD!

 

[Honza1]

There are multiple things which cause this. I have similar issues with some of my disks, so I looked into this.
1. TM can run thinning. But TM will tell you that, so if you look at TM icon and click on it, it states something about it.
2. Spotlight may be indexing the TM disk. I suspect that this is needed for TM to function correctly.
3. Disk itself may be doing this. If you have SMR magnetic disk (as oppose to CMR), the disk records data fast in available space first (any available space) and later, when it is not being used, it will rearrange the data which results in more efficient storage. Google :"CMR vs SMR Hard Drives" to see what I mean. It is not easy to figure out what disk you have... In this case it is not the system doing this, it is the disk which runs on its own. And if you do not let it do this sometimes, it will eventually slow down a lot.

Yes, as SSDs are becoming cheaper and cheaper, TM on SSD sounds like great idea.