OPERATING SYSTEM - DISK SCHEDULING
Disk Scheduling is done by Operating systems to schedule I/O
requests for the disk.
Disk scheduling is also known as I/O scheduling.
requests entertained in the order they arrive in the disk queue.
tracks which are closer to current disk head position are serviced first.
head starts from one end of the disk and moves towards the other end, servicing requests in between.
Modified version of SCAN. as soon as the head reaches the other end, it immediately returns to the beginning of the disk.
services request similarly as SCAN, meanwhile it also “looks” ahead as if there are more tracks.
uses the idea of wrapping the tracks as a circular cylinder, seek time is better than C-SCAN.