A A measure of how quickly multiple small files can be read from a device.4K random read is a disk access pattern whereby small (4K) blocks of data are read from random locations on the surface of the device being tested at a queue depth of one. The term is used primarily within the context of benchmarking and the speed which it is usually measured in, MBps, can be thought of as how effective a device is at quickly retrieving small pieces of data from random locations. This type of access pattern is very common during operating system startup, where lots of configuration and driver files must be read from the disk. Drives that are used to host operating systems will perform much better if they are able to sustain high random read speeds. As a rule of thumb approximately 20% of a typical users overall disk access on a PC will consist of random reads.