how do i know if the computer is booting from the main drive and not from the external drive
Shut down, detach the external drive and startup. What happens? You then can look and determine exactly what drive your using.
You're welcome.
Another way to choose between drives during startup is to use the Startup Manager.
see > Change your Mac startup disk - Apple Support
Easy, check the startup drive in System Preferences.
Change the default background wallpaper if you want an easy visual reference/reminder of which one is currently booted. You can also change the volume name of one of them assuming you have the mounted volumes shown on the Desktop or you look on the Finder's sidebar. The background wallpaper will be the most noticeable reminder though. Of course if you are cloning & updating the second drive from the internal drive, then none of this really works depending on the method being used.
One is the internal drive and one is the external drive.
If they have the same name, then you may be able to tell the difference by the color of the drive icon. Silver/White for the internal and Orange/Yellow for the external drive.
In the Startup Disk preference, highlight the drive that you wish to startup from and then click Restart.
There are 2 drives in startup which one is starting up
Thank you very much that's helpful.
Can I close down and remove the USB drive safely .won't let me close it down as its being used
how do i know which drive I am booting from main of usb
