Backing up OS Sierra

You can use a cloning software like SuperDuper! or CarbonCopy Cloner.

It's very easy, just choose the source volume and destination then copy.

Once you've made the clone you can then just clone the OS back to the new drive.

I'm not sure why you would want to copy just Mac OS, don't you want your files also? TM does back them up but it would be another step to retrieve them TM.

If all you want is the OS, the easier way to do that would be without SD. In Recovery Mode just choose to install Mac OS.

How to reinstall macOS - Apple Support

Yes, SD is the one I use for cloning. I keep 2 backups, one with Time Machine and one with SD.

The advantage of the clone is that you can boot from it and use the system. So, if your hard drive fails you can just boot from the backup and keep on working until you have the time to repair or replace the internal drive. You can also drag and drop files with the clone because it is the identical file structure on your primary drive.

The advantage of TM is that it creates recursive backups, so you can restore a file or the entire drive from a certain point in time.

franca63 wrote:

I downloaded super-duper and I'm trying to clone my OS High Sierra to an external hard drive. After I open Disk Utility, on the side bar under internal does not say High Sierra, it does show MacIntosh HD, if I click on that will it clone my whole hd? I just want to make a duplicate of OS High Sierra. In the Super Duper app it asks for the source, do I select MacIntosh HD?

You don't need to use Disk Utility for anything. In SuperDuper! in the "From" field choose "SuperDuper!" and in the "To" field choose Macintosh HD. In the "Using" field choose Back up - all files. That will clone your entire system to the Macintosh HD.

If you just want to copy back select files you can either use the Recovery method I described, or you can use the full clone and then delete the files you no longer want. Or, you can delete the files you no longer want before cloning from the old drive.