Current mobile devices, like mobile phones, tend to in-
clude dierent appliances and applications such as word ed-
itors, spreadsheets, photographic and video cameras, which
usually produce a large number of les that can exceed the
storage capacity of these devices. This situation can be faced
by using external storage system (eg. a PC) to backing up
les and thus giving to mobile devices new available stor-
age space. The common backup system in mobile devices