Como Grabar Pantalla En Mac Os

I'm not using VMs, the VM service hasn't run since I first set up my server. I have the isos share set to use the cache. However, I sometimes have an empty isos folder appear on one of my storage drives. I expect it to stay there (and empty) on my cache array, but why is it appearing on a storage drive? Under Cache, it is set to YES:Cache (not prefer).