We report experiments and modeling of translocation of double-strand DNA through a siliconoxide nanopore. Long DNA molecules with different lengths ranging from 6500 to 97000 base pairs have been electrophoretically driven through a 10 nm pore. We observe a power-law caling of the translocation time with the length, with an exponent of 1.27. This nonlinear scaling is strikingly different from the well-studied linear behavior observed in similar experiments performed on protein pores. We present a theoretical model where hydrodynamic drag on the ection of the polymer outside the pore is the dominant force counteracting the electrical driving force. We show that this applies to our experiments, and we derive a power-law scaling with an exponent of 1.22, in good agreement with the data.