Do partitions re-size themselves?

Question

I am using a four-bay Drobo for my Time Machine backups and created a single partition using Disk Utilities that I hoped would be small enough that TM would be triggered to delete old backups before the drives were full.  The Drobo can be formatted for way more space than the actual capacity of the drives, so I made a 3 TB partion out of a possible 16 and did nothing with the rest.  Meaning I could have made a second partition with 13 TB (I'm really rounding my numbers for simplicity's sake...) but didn't.  Now I am finding there is more backup than my 3 TB - it's like 3 1/2 TB now - and Disk Utility tells me there is still only one partition, but that it takes up the whole potential 16 TB now.  Will it do that? fill the space on its own without asking me?  Do I need to fill the leftover space with a second partition in to keep the first one from "expanding" on its own?

Answer 1

Thank you so much for the offer, Peter, but I think I may be close to solving the problem. I think it's something to do with the fact that some of the photos have been cropped and therefore the 'constrain proportions' command is not appropriate. I don't think you'd want to read my diary and the photos are somewhat personal as they're of my late mother's funeral flowers .... enough said. So I will persevere and try and work it out myself. Thanks for all your efforts.