The differences between Linux IO Schedulers
The Linux kernel input/output scheduler (IO Schedulers) controls the way the kernel handles read/write to disks. Different I/O schedulers may have different impact on certain workloads. Here are the list of available Linux I/O schedulers:
Noop scheduler is the simplest IO scheduler available in the kernel. It does not perform sorting or seek-prevention. It is intended for devices that has no mechanical parts or is capable of random access such as SSD or flash-disk.
2) Anticipatory (AS)
Anticipatory is the default I/O scheduler for Linux kernel (2.6.x) until it was replaced by CFQ. It tries to optimize disk I/O by minimizing disk seeking/head movement whenever possible.