Cache coherence in parallel and distributed file systems.

Disclosed herein is a motor driven wiper device particularly for use with side-view mirrors on vehicles. A vertically or horizontally disposed wiper blade is mounted on a support arm and sweeps the surface of a side-view mirror in order to prevent the accumulation of debris or moisture which can interfere with rear view vision. The wiper blade support arm is normal to and slidably disposed on two transversely mounted rods, so that the wiper support arm sweeps back and forth along the length of the transverse rods. Two linkage arms located on the back face of the mirror connect the wiper support arm to the drive motor. The drive motor, and thereby the wiper blade, can be actuated from inside the cab of the vehicle.