SCAN 算法又称电梯调度算法。SCAN算法是磁头前进方向上的最短查找时间优先算法，它排除了磁头在盘面局部位置上的往复移动，SCAN算法在很大程度上消除了SSTF算法的不公平性，但仍有利于对中间磁道的请求。-SCAN algorithm, also known as elevator scheduling algorithm. SCAN algorithm is the shortest on the head to find the forward direction of time priority algorithm, which excludes the local position in the disk head back and forth on the move, SCAN algorithm largely eliminates the SSTF algorithm is not fair, but there is still beneficial to the middle track the request.