Why would companies assess quality of service for VMs?

Generally, companies use quality of service (QoS) tools or address quality of service concerns for virtual machines and virtualization environments for the purposes of improving those environments, or for making workflows more effective and designing distributed systems in a more efficient way.

For example, exploring quality of service options for a set of virtual machines can help solve a “noisy neighbor” problem – a situation where a particular virtual machine takes up more resources than its neighbors and impacts the performance of other network components. Quality of service can be applied to specific systems such as Hyper-V storage, or used in the context of virtual machine clusters to show the load for each machine and other metrics. Cluster quality of service reports for virtual machines can help show demand on the machines over time, as well as where machines are located in the data center, CPU thresholds, memory thresholds and more.

In an overall sense, quality of service resources help to allocate resources in a more efficient way. They allow companies to do more with less in a virtual machine setup. Experts note that one alternative to quality of service work is the practice of over-provisioning, where companies simply throw more resources at a set of virtual machines to enhance performance. Obviously, quality of service work would lower costs for these sorts of situations. Vendors and other parties offer QoS tools and services to enterprise clients; for instance, Microsoft maintains a set of QoS resources for users.