A method to write information to, or retrieve information from, an information storage medium disposed within a portable data storage cartridge moveably disposed in a data storage and retrieval system, wherein the data storage and retrieval system further comprises a data storage device. The portable data storage cartridge comprises a moveable curved door slidingly disposed within the enclosure, and a tape reel rotatably disposed within the enclosure, wherein the moveable curved door and the tape reel are non-concentric. The method retrieves the portable data storage cartridge from a storage slot, transports that portable data storage cartridge to a data storage device, disposes the portable data storage cartridge in the data storage device. The method further moves the moveable curved door from said a position to a second position, and reads information from and/or writes information to, the information storage medium.