Help with trying to boot from an External Drive?

[Tsurisuto]

I'm trying to boot from an external drive, but when I hold down the "Option" (alt) key on startup, I just get a grey screen with a padlock icon on the left and a arrow on the right.

What do I need to do in order to allow Target Disk Mode?

 

[xUKHCx]

I'm trying to boot from an external drive, but when I hold down the "Option" (alt) key on startup, I just get a grey screen with a padlock icon on the left and a arrow on the right.

What do I need to do in order to allow Target Disk Mode?

Sounds like someone has enabled firmware password protection. If you know the password then enter it in the box. You could boot up and in system preferences choose the external as the boot drive (don't think this will work as a work around though). I don't know of any work arounds if you don't know the password.

Is this the image you see

If so check out this page for more info about it

 

[Tsurisuto]

Thank you. I remembered the password and it allows my to use Target Disk Mode now.

Cheers for that.