A storage subsystem contains multiple non-volatile memory arrays that are accessible to a host system when the storage subsystem is connected thereto. The storage subsystem implements commands and/or modes for enabling the host system to create and use backup copies of files, such that the host system can recover when files become corrupted or otherwise lost. In one embodiment, the storage subsystem presents the non-volatile memory arrays to the host's operating system as distinct storage devices (e.g., ATA device 0 and 1), and implements special commands for copying data between these storage devices. The subsystem may alternatively present the memory arrays to the host operating system as a single storage device. The storage subsystem may have a standard form factor, such as a form factor commonly used for memory cards.