VMware has released two technical whitepapers regarding storage I/O control: “Storage I/O Control Technical Overview and Considerations for Deployment” and “Managing Performance Variance of Applications Using Storage I/O Control”.
Although these papers aren’t specifically geared towards VDI I think that SIOC can be of use to VDI environments. Storage I/O Control (SIOC) provides storage I/O performance isolation for virtual machines, thus enabling VMware® vSphere (“vSphere”) administrators to comfortably run important workloads in a highly consolidated virtualized storage environment. It protects all virtual machines from undue negative performance impact due to misbehaving I/O-heavy virtual machines, often known as the “noisy neighbor” problem. Furthermore, the service level of critical virtual machines can be protected by SIOC by giving them preferential I/O resource allocation during periods of congestion. SIOC achieves these benefits by extending the constructs of shares and limits, used extensively for CPU and memory, to manage the allocation of storage I/O resources. SIOC improves upon the previous host-level I/O scheduler by detecting and responding to congestion occurring at the array, and enforcing share-based allocation of I/O resources across all virtual machines and hosts accessing a datastore. With SIOC, vSphere administrators can mitigate the performance loss of critical workloads due to high congestion and storage latency during peak load periods. The use of SIOC will produce better and more predictable performance behavior for workloads during periods of congestion.