I often have multiple virtual machines for different purposes. Some I keep idle, some I destroy and recreate when needed, and some I use for actual work and they stay there forever.
Recently I ran out of space. It was not really bad planning on my side, I just didn't have more space to allocate at the moment. I got a new disk to dedicate just to VMs. The new disk is faster but it's not very big; if I'm not careful I will run out of space again.
I decided to move some virtual machines; just the ones that have a GUI. The server based ones that are not interactive can stay in the old and slightly slower disk.