I'm looking to upgrade a 120GB SSD in my late 2009 iMac (21.5in) to a 250GB SSD. My mac is running the latest version of MacOS.
I have an external USB drive which I will be setting up to create a Time Machine backup. My understanding is that once the backup has completed, I swap my internal SSD with the new SSD. Then, with keeping the USB Drive with Time Machine backup on it connected, I boot to it and some sort of Disk Utility software will walk me through restoring the Time Machine backup to my newly installed drive.
This is all good, but I have read mixed information about whether or not the Time Machine backup includes a complete backup of data and OS or if I will need to install the OS onto the new drive and update it before restoring from the Time Machine.
I don't have a physical copy of the OS, so it concerns me a little. It's a second-hand Mac and came with El Capitan installed.
Does a Time Machine backup contain the OS as well so it's as simple as boot to a Disk Utility and tell it to restore from Time Machine to the new SSD?
My first Mac, so thanks for any help!