[zenlinux]

Thus speaketh the kernel source:

The "anticipatory" I/O scheduler is the default disk scheduler. It is generally a good choice for most environments, but is quite large and complex when compared to the deadline I/O scheduler, it can also be slower in some cases especially some database loads.

The deadline I/O scheduler is simple and compact, and is often as good as the anticipatory I/O scheduler, and in some database workloads, better. ...

The CFQ I/O scheduler tries to distribute bandwidth equally among all processes in the system. It should provide a fair working environment, suitable for desktop systems.