Purgeable space...what the !??!

OK, I kinda get it, Apple is saying you can dump some stuff off your drive to the cloud, is that it? But what if I want to see how much space I have PHYSICALLY?

And how the heck can it tell me I have 9.6 GB of space on an 8 GB SD Card?
Capacity: 7.98 GB
Available: 9.79 GB (3.61 GB purgeable)
Used: 1.81 GB
Is there ANY way this makes sense??? Can I tweak a setting to have OS X show me how much space I can actually copy to?

 

bump...anyone?

 

https://apple.stackexchange.com/a/253944

 

OK, sure, a pretty clear explanation "These are files that the system, or you, hasn't accessed in a long time and so are stored in iCloud. If you're running low on disk space, macOS can safely delete them, keeping a 'shortcut, on your system. When you need the file again, the system will download it for you in he background. "
but it doesn't really explain how "available" can be more than the actual size of a removable media...there's no way to stick 9.6 GB on an 8 GB USB at least in the universe as we know it. It's annoying to have to tray and calculate in my head how much more space there ACTUALLY is, unless I'm totally misunderstanding something.

 

This is more for non-removable storage typically used by iPhones and iPads. Due to the limited storage, people can hit their ceilings pretty quickly. An iCloud account makes it so that storage is mirrored for most files. Those files are copied so if you delete the copy stored physically on your device, it'll still be available through iCloud.

If you have file X, it's then copied into iCloud. You then delete file X because you need more space on your iPhone (for instance). With the newfound space, you fill it up with file Y. Eventually, that file is copied as well. Now, you want to reclaim that space to put something else on it ; file Z. And so on so forth. Now, let's say all those files were 1GB each. That's 3GB that were uploaded to iCloud, yet only 1GB is still taken by file Z. You delete file Z and now have that 1GB of physical storage space available to be used right then and there. But the amount of storage space taken in your iCloud account continues to rise because you keep replacing the newfound space with new files.

You could keep rotating files and delete/reuse the space to the point where you'd have a database or catalog of hundreds of gigs, even if your iPhone can only physically hold (let's say) 16GB at a time.

 

OK, I get that. And the USB case is just kind of an oversight or accident...though I guess it could be used in the same manner, just not in my application. Cool, thanks so much for the explanation!

 

Purgeable means empty your trash. I think, anyway.