I have a 21.5 late 2012 iMac with Thunderbolt 1 port. It has become very slow. With this external connected drive connected in Thunderbolt, is it possible to put everything on it (the OS system as well as all the contents of the current hard drive)?
In theory this is possible, but the work requires some specific knowledge. However, the slowness problem could be caused by another component, it is possible that the problem remains after transfer.