With sequential access, the diskhead can move directly to the next available track on the disk.
使用顺序访问，磁盘头可以直接移动到磁盘的下一个可用磁道。
2
As mentioned above, random access requires the diskhead to move randomly over the disk to find the proper data points.
正如上文提到的，随机访问要求磁盘头能随机移动到磁盘上，查找对应的数据点。
3
Then, the server's diskhead had to move randomly over all areas of the disk to get to the proper track and sector for the data that was changed or updated.