
There are some third-party applications available in the market which lets you make a full clone backup on the external hard drive which will also boot like the internal drive.

There is a built-in utility app in Mac OS which lets you create a clone of your entire hard drive, but it will not boot if you lost your built-in drive or having startup issues with your Mac. In any case, creating a clone copy of your entire Mac system files and also makes it bootable as the same copy of your Mac OS drive is very handy in these cases which are mention above or you name it.

Backup Mac, before you lose your hard drive, dead for any reason or having a startup problem with your Mac or just want to save your projects and office work on urgent bases or want to save family photos or videos.
