MAID (massive array of idle disks) is a storage technology in which only those disk drives in active use are spinning at any given time. MAID reduces power consumption and prolongs the lives of the drives.
A MAID, which can have hundreds, or even thousands of individual drives, offers mass storage at a cost per terabyte roughly equivalent to that of tape. MAID technology is offered as an option to high-volume tape libraries.
When MAID is implemented, every drive is periodically tested. If a drive shows signs of failure, data is transferred to other drives. A MAID has far greater storage density than a RAID (redundant array of independent disks) system of equal cost. In addition to reducing power consumption, the cooling requirements of MAID are also reduced.
Limitations of MAID include lower throughput than conventional disk arrays and longer latency times while inactive disks spin back up.