Materials exhibiting-persistent spectral hole burning via a gated mechanism are promising candidates for the development of frequency domain optical storage with storage densities beyond 10 to the 9th power bits/sq. cm. Gated hole burning requires a secondary gating field for writing, permitting nondestructive reading in the absence of this field. Properties of gated hole burning materials suited for a practical storage system are analyzed with particular attention to the required values of absorption cross section, density of centers, and effective hole burning materials for storage applications. Some general guidelines for photon gated mechanisms using three level and four level systems are presented. Keywords: Persistent spectral hole burning; photon gating; frequency domain optical recording.