I have a mid-2011 iMac with a 256 flash SSD and a 1 TB SATA disk HD. I am almost out of room, storing photos and videos - and do not want to delete files to make space. I am looking for help on what my options would be to improve my storage issue. Is there an additional bay - could I have another hard drive installed (HD 3)? How feasible is it to install a 4 TB hard drive in the place of the current 1 TB drive? Is there a drive that will work better than others? No fan issues, etc.? Is there an external drive that is recommended? This is my least favorite option as I like the simplicity of an internal drive that is automatically backed up with my Time Capsule. Any ideas?