What happens to caches when you lose them?

[ksirul]

When things get unrendered and you rerender, do the old caches still exist on the disk and take up space or do they get deleted somehow when they get unlinked?  If they do still exist, is there a way to delete unused caches?

[BKM]

Everything is on the framestore (media storage) and should be managed by Smoke.
Eventually those unused cache files will get deleted when you restart smoke/ reboot mac.

VIC (Volume integrity check) runs and deletes unused frames from the Media storage. 

So while working, unrendering doesn;t immediately delete the files. Which is why you can undo a cleared render.