Reinstall OS X 10.10.4 onto external thunderbolt SSD
Hi folks,
I'm new here so I apologise in advance if I'm not following some of the specific forum protocol...
iMac mid-2011
i5 2.5 Ghz
4 GB Ram
Running Yosemite 10.10.4
stock 500 GB 7200 rpm HDD
Basically I just bought a new samsung 850 evo (250 gb) and a RocketStor 5212 Thunderbolt Dock, because I'm not too comfortable opening up the Mac to stick a new drive inside. What I'm looking to do is clean install the OS onto the external thunderbolt SSD without wiping the contents of the internal HDD, and I do not want to open the mac.
Is it possible to install the OS onto the thunderbolt SSD and then basically use the internal 500 GB drive as a drive for data storage without reformatting the internal drive, and maybe somehow delete the OS from the internal HDD?
iMac (21.5-inch Mid 2011), OS X Yosemite (10.10.4)