I/O contention (input/output contention)

I/O contention (input/output contention) is the degradation of performance that occurs when a disk or virtual machine competes for I/O resources.  I/O contentions are often seen in instances of heavy workloads when there is a high number of reads and writes, causing latency and bottlenecks. For example, the more virtual machines in an environment, the higher the risk for I/O contention. Storing heavily accessed files on the same disk will also increase the risk of contention.

In general, the word contention is used in computing to describe a situation in which two or more devices compete for the same resources. 

See also:  I/O blender