Disk encryption is essential for physical computer security, but seldom used due to the trouble of remembering and typing a password at every restart. We describe Mandos, a program which solves this problem, its security model, and the underlying concepts of its design, and some of its evolution over the 10 years since its initial release. Any security system must have a clear view of its intended threat model – i.e. what threats it is actually intended to protect against; the specific choices and tradeoffs made for Mandos will be explained. Another danger of security system design is the risk of its non-use; i.e. that the system will not be used for some real or perceived drawbacks, such as complexity. The deliberate design choices of Mandos, involving low-interaction, “invisible” and automatic features, will be covered. If possible, the many necessary changes made since the last FOSDEM talk in 2015 will also be described.