All your files contain intimate, artistic, confidential, professional, administrative elements... They are virtual and their existence depends only on the material support on which they are recorded. Thus, the threats of the physical world hover over the files of the virtual world. The threats are the risks incurred by these physical supports. They are innumerable, but they include: theft, breakage, wear and tear, fire, loss. Still not well known by the general public, computer backup is a rapidly growing field that echoes the increase in data loss by companies and individuals. For companies, the issue is commercial, while for individuals it is a sentimental one.