Disk Head Scheduling


More than one request in the disk queue - read or write
### Algorithms
- FCFS - fair but ineffcient - fifo
- SSTF - starvation possible - select minimum seek time - **usual algorithm**
- SCAN - elevator algorithm - possibility of double time - double direction
- C-SCAN - one direction since disk is round - **usual algorithm **- provide uniform wait time
- LOOK - one direction until services all requests → reverse
- C-LOOK - variant of C-SCAN - only goes as far as the last request in each direction