Updating the live system

Any time you make a change to your Debian-on-USB system that needs to be persistent, you will have to run the moo command. The moo command compares the /cow (ramdisk partition) with the underlying squashfs filesystem(s), and writes any changes to a new squashfs, stores it on the USB boot media, and inserts it into the unionfs.

Due to the limitation of the linux kernel for only mounting 8 loop devices, moo will create a new base image after 7 partial images are created. When this happens, moo will inform you that a reboot is desirable. I suggest following this advice, because additional backups cannot be created after this, without unpredicatable results.