Understanding the Market and Virtual Currency
To perform application resource management, IWO models the environment as a market and then uses market analysis to manage resource supply and demand. For example, bottlenecks form when local workload demand exceeds the local capacity—in other words, when demand exceeds supply. By modeling the environment as a market, IWO can use economic solutions to efficiently redistribute the demand or increase the supply.
IWO uses two sets of abstraction to model the environment:
• Modeling the physical and virtual IT stack as a service supply chain: The supply chain models your environment as a set of managed entities. These include applications, VMs, hosts, storage, containers, availability zones (cloud), and data centers. Every entity is a buyer, a seller, or both. A host machine buys physical space, power, and cooling from a data center. The host sells resources such as CPU cycles and memory to VMs. In turn, VMs buy host services and then sell their resources (VMem and VCPU) to containers, which then sell resources to applications.
• Using virtual currency to represent delay or QoS degradation, and to manage the supply and demand of services along the modeled supply chain: The system uses virtual currency to value these buy/sell transactions. Each managed entity has a running budget. The entity adds to its budget by providing resources to consumers, and the entity draws from its budget to pay for the resources it consumes. The price of a resource is driven by its utilization—the more demand for a resource, the higher its price.
Figure 5-6 illustrates the IWO abstraction model.
Figure 5-6 IWO abstraction model
These abstractions open the whole spectrum of the environment to a single mode of analysis—market analysis. Resources and services can be priced to reflect changes in supply and demand, and pricing can drive resource allocation decisions. For example, a bottleneck (excess demand over supply) results in rising prices for the given resource. Applications competing for the same resource can lower their costs by shifting their workloads to other resource suppliers. As a result, utilization for that resource evens out across the environment and the bottleneck is resolved.
Risk Index
Intersight Workload Optimizer tracks prices for resources in terms of the Risk Index (RI). The higher this index for a resource, the more heavily the resource is utilized, the greater the delay for consumers of that resource, and the greater the risk to your QoS. IWO constantly works to keep the RI within acceptable bounds.
You can think of the RI as the cost for a resource, and IWO works to keep the cost at a competitive level. This is not simply a matter of responding to threshold conditions. IWO analyzes the full range of buyer/seller relationships, and each buyer constantly seeks out the most economical transaction available.
This last point is crucial to understanding IWO. The virtual environment is dynamic, with constant changes to workload that correspond with the varying requests your customers make of your applications and services. By examining each buyer/seller relationship, IWO arrives at the optimal workload distribution for the current state of the environment. In this way, it constantly drives your environment toward the desired state.