external SSD won't show free'd up space (after emptying bin)

thanks for the education on volumes, that's good info for me.

I have solved my problem though (so I don't need to reformat). Seems the snapshots were being created by my file copying utility, Carbon Copy Cloner. Having read through their documentation (after being pointed there by their tech support, who I wrote after seeing that the names of the "offending" snapshots were prefaced by their company name), I now know that CCC has a policy of creating backup snapshots on volumes where it's being used, and that the default "maintain free space" policy is 30GB, exactly the amount that my 4TB SSD has (and had) free. So if I turn off CCC's snapshot policy, and delete those snapshots, I'll have all my space back (i don't need those snapshots, as I use an 18GB Time Machine volume, as well as have multiple redundant copies of all the data on that drive).

So, problem solved (and would have been solved earlier if I'd RT FM, I'm kinda kicking myself).

Thanks very much for your help, I really appreciate it!

hi HWTech, thanks for your helpful reply.

I've solved my problem (see my recent reply to P. Phillips), but your question about what app I'm using to back up my drive was right on the mark, as it was exactly that app (Carbon Copy Cloner) that was creating the snapshots that were taking all my room (I'm a timelapse photographer, and regularly create 200-500GB per shoot. I move data around in blocks that large, thus the very large snapshots).

Again, thanks for your help.

followup: interestingly, "About this Mac" says I'm running 12.4, but I booted into Recovery mode, and Disk Utility says I'm running 12.6.3 (I thought I'd not prevented any updates from happening, as that's not like me). I'm not sure what to make of this disparity.

And I've deleted two blocks of 500GB (one today, one over a week ago), sorry to not be clear. It was deleting the latest one, and not seeing any space free up, that led me to post.

not sure if you're misunderstanding me: the problematic drive is just holding data, I'm not starting from it.

Back in the day, booting into recovery mode booted from a small partition that held a copy of the OS. I'm assuming that it's still that way now, and therefore that small partition is running OSX 12.6.3, and my normal boot partition is, mysteriously, only running 12.4. My only option, in System Preferences --> Software Update is to upgrade to Ventura, not to 12.6.3.

That mystery aside, I still need to find a way to get the OS to properly free up space on this external SSD :-)

Hi, thanks for your reply.

I deleted the 500GB over a week ago. And just to be clear: this is an external SSD, and not the boot drive.

It's a good point re: latest Monterey.

I should've delved deeper before coming here (and I'm usually a very delving type!).