Disk Scheduling: FCFS, SSTF, SCAN & C-SCAN

Every operating system keeps a queue of pending disk I/O requests, and the order it services them in is governed by a disk-scheduling algorithm — one of the classic mechanisms an OS kernel uses to turn "what the programs asked for" into "what the hardware actually does." This simulator renders a real hard-disk cylinder track in 3D: a read/write head sweeps toward a queue of pending requests under First-Come-First-Served, Shortest-Seek-Time-First, SCAN, C-SCAN or LOOK, while a live graph above the track traces the classic seek-pattern chart used to compare these policies. Switch algorithms on the same request queue to see how total head movement — and therefore total seek time — changes, watch requests turn from pending amber to serviced green as the head reaches them, and read live total and average seek-length numbers as the sweep runs.