This paper presents Mosaic a practical and secure e-voting system. Compared to existing remote e-voting systems, Mosaic is practical since it deals with availability, ease of usage and scalability in addition to the implementation of an efficient security scheme. We demonstrate that the adaptable architecture of Mosaic system enforces the system scalability and performability by evaluating the system on the French grid, grid 5K. An embedded management system allows for Mosaic self-adaptation in front of failures or security attacks without breaking the security properties of the system.