Western Digital today expanded its MyBook line of external hard drives with its first redundant backup drive. Dubbed MyBook Mirror Edition, the new two-drive external storage system comes out of the box set up in a RAID 1 mirror that automatically backs up one drive’s information on the second.

For those interested in maximum capacity rather than maximum security, the dual drives can be easily converted to a RAID 0 configuration – allowing the full volume of storage space to function as a single drive or else use each drive separately. The storage device works without a fan, so it operates quietly, and its accessible casing lets users easily replace a faulty drive if needed.

The My Book Mirror Edition connects through USB and is available immediately from both Western Digital’s online store and retailers. The 1TB version sells for $289.99, while the 2TB version goes for $549.99.