An optical information storage system using optical storage media including multiple data layers or stacks wherein each of the multiple data stacks has a storage density comparable to a conventional single layer optical disk. The optical data storage system comprises an optical medium having a single dedicated servo layer and multiple data stacks which each contain an embedded servo format, a servo laser beam positioned to maintain a first focus point on the dedicated servo reference layer, a read-write laser beam positioned to maintain a second focus point on one of the data stacks, a first, dedicated servo system which provides focus and tracking error correction according to error signals generated from the dedicated servo layer, and a second, embedded servo system which provides focus and tracking error correction according to error signals generated from the data stacks. The dedicated servo layer, in different embodiments of the invention, may be positioned either below or above the data stacks in the optical medium, or interposed between data stacks. The data stacks may comprise discrete physical data layers or "e;virtual"e; data layers defined by a format hologram. The servo and read-write lasers may differ in wavelength and/or polarization.