RAID is an abstraction layer on top of the physical disks. RAID 1 (mirrored drives) is similar to what the IA have described, but it sounds like they are creat

RAID is an abstraction layer on top of the physical disks. RAID 1 (mirrored drives) is similar to what the IA have described, but it sounds like they are creating their mirrors using simple file system commands (or tools like rsync) rather than introducing the complexity and overhead of hardware/software RAID. Other forms of RAID (e.g. RAID 5/6) where data is spread across an array of drives with parity, would provide the IA with additional redundancy but at the expense of significantly increased cost and complexity.