A repository does not always have all annexed file contents available. When you need the content of a file, you can use "git annex get" to make it available.

We can use this to copy everything in the laptop's annex to the USB drive.

$ cd /media/usb/annex
$ git annex sync laptop
$ git annex get .
get my_cool_big_file (from laptop...) ok
get iso/debian.iso (from laptop...) ok