DADS: dynamic and automatic disk scheduling

The selection of the right I/O scheduler for a given workload can greatly improve the performance of a system. But, this is not an easy task because several factors should be considered, and even the scheduler deemed the "best" can change at any moment. So, we present a Dynamic and Automatic Disk Scheduling framework (DADS) that compares different Linux I/O schedulers and automatically and dynamically selects that which achieves the best performance for any workload. The implementation described here compares two schedulers by running two instances of a disk simulator inside the Linux kernel, each one having a different scheduler. Our proposal compares the schedulers' service times, and changes the scheduler in the real disk if the performance is expected to improve. DADS has been analyzed by using different workloads, hard disks, and schedulers. Results show that it selects the best scheduler of the two compared at each moment, improving the performance and exempting system administrators from selecting a suboptimal scheduler.