Grids are widely used by CPU intensive applications requiring to access data with high level queries as well as in a file based manner. Their requirements include accessing data through metadata of different kinds, system or application ones. In addition, grids provide large storage capabilities and support cooperation between sites. However, these solutions are relevant only if they supply good performance. This paper presents Gedeon, a middleware that proposes a hybrid approach for scientific data management for grid infrastructures. This hybrid approach consists in merging distributed files systems and distributed databases functionalities offering thus semantically enriched data management and preserving easiness of use and deployment. Taking advantage of this hybrid approach, advanced cache strategies are deployed at different levels to provide efficiency. Gedeon has been implemented, tested and used in the bioinformatic field.