I'm sorry as I realize this is an older thread. So I failed to do my due dilligence prior to buying a new SSD for my wife's Mid 2011, 21.5 iMac. I wanted to know if this is possible. I want to install the SSD in the spare bay behind the optical drive. prior to doing that was thinking I would clone the HDD to the SSD, then wipe the HDD. This way the iMac runs the OS from the SSD and has another storage drive. it is Mid 2011 model so I do not have much faith the HDD has much life left in her so want to transfer the OS and other valuables off of it. Figure I will use it for nonessential things. I have a 2 TB Lacie external HDD that I would place anything super important onto. Does this plan sound too difficult or is it possible?