A description is given of an optical storage system comprising an optical storage medium (1) and an optical head device (6). The medium has a substrate (2), a recording stack (3) and an optically transparent protective coating stack (4 and 5), for protecting the recording stack from impact by the optical head device (6). The protective coating stack comprises a multi-layer (4 and 5) of at least: a first layer (5) with a thickness smaller than 40 nm and a surface with a surface energy smaller than 1.5 J/m.sup.2, and a second layer (4), adjacent the first layer (5), with a Young's modulus E smaller than 10 GPa and larger than 0.001 GPa. This combination of layers (4 and 5) is very resistant to damage caused by mechanical impact of the optical head device (6). No lubricants are required.