The present invention relates to vacuum pumps and a method for creating and maintaining a high vacuum. A vacuum pump includes a regenerative section and a turbo-molecular section. A common first rotor carries forward-rotating elements of both the regenerative section and the turbo-molecular section. Additionally, a second rotor carries counter-rotating elements of the turbo-molecular section. A first drive rotates the first rotor in a forward rotational direction while a second drive rotates the second rotor in a counter-rotational direction. The drives may be controlled to drive the common first rotor on start-up, and to later drive the second rotor.