Massive Arrays of Idle(inactive) Disks

MAID是英文“Massive Arrays of Idle Disks”的缩写，中文意思是大规模非活动磁盘阵列存储。它是最新的分级存储技术之一。

    MAID的原理类似于磁带库中的磁带一样，只有需要时才将一部分磁盘开机运转，而其他磁盘通常处于断电状态。从这种意义上讲，MAID也可以称作为磁盘库。因此，MAID中所有的磁盘（目前主要是SATA磁盘）并不是每时每刻都是活动的，MAID子系统中大部分磁盘处于睡眠（断电）状态，直到系统发出请求。SATA磁盘启动的时间大约为10秒。

 

In a MAID, rack-mounted disk arrays have all inactive disks powered down, with
only the disk controller alive. When an application asks for data, the controller powers
up the appropriate disk drive(s), transfers the data, then powers the drive(s) down
again. By powering down infrequently accessed drives, energy consumption is significantly
reduced, and the service life of the disk drives may be increased.