Disk Head Scheduling

method of ordering disk requests
- based on cylinder number
- moving the arm inwards and outwards along the disk surface is the slowest mechanical operation
three parts:
- seek time: time for head to move to appropriate track or cylinder
- latency time: time for desired block to rotate under the read-write head
- transfer time: time required to transfer data between disk and main memory
try to do operations on nearby cylinders at about the same time
disk requests can be reads or writes; can be used for swapping, paging, or file use

Howard Hamilton
Wed Feb 2 10:00:00 CST 2000