fio is an I/O tool meant to be used both for benchmark and stress/hardware verification. It has support for 4 different types of I/O engines (sync, mmap, libaio, posixaio), I/O priorities (for newer Linux kernels), rate I/O, forked or threaded jobs, and much more. It can work on block devices as well as files. fio accepts job descriptions in a simple-to-understand text format. Several example job files are included. fio displays all sorts of I/O performance information, such as completion and submission latencies (avg/mean/deviation), bandwidth stats, cpu and disk utilization, and more.