Abstract: Methods, systems, and computer readable media are provided for accessing and compressing data stored in a media library, as well as tracking optical media with media tags and cartridge manifests within a library. In one embodiment, a simulation layer of a hybrid storage appliance allows libraries of optical media with write-once read-many (WORM) properties to look like logical block devices with non-WORM characteristics. In another embodiment, data from a user's files is compressed by the media library appliance in chunks in such a way that coarse granularity seeking is possible within a compressed user file. In another embodiment, a media cloud is used by a hybrid storage appliance to seamlessly recover from failures in optical media, library robotics, optical drives, and network connections during the creation, recovery, and distribution of data. In another embodiment, cartridge manifests and media tags are used to track optical media within a library.