I finally got a 2016 rMB m5 to replace my 2011 11" MBA. I want to begin transferring data over from the MBA to the rMB. I have an external HD (Western Digital) from 2011 and use it for Time Machine. I only back up every few months and decided to obviously back up my MBA one final time so I can use Migration Assistant and start loading stuff onto my rMB. The problem I ran into was it wouldn't begin the backup unless I encrypted the external HD. So I went ahead and did so, only for it to take all night and then some (probably over 8-9 hours). What is the exact point of this? I just wanted to back up my MBA on final time and use migration assistant to transfer the data or use one of the back ups to restore on my new rMB. Now the external HD is being encrypted. Am I going about this wrong? If this was going to take this long I would just have done it over wi-fi.