3.2.1 Service Design Parameters
As part of the design process for the Committed service offering, providers should pay special consideration to key service settings and values in vCloud Director that can affect service performance and consistency levels for a subscriber’s organization virtual datacenter. Despite use of the Allocation Pool allocation model in this service, circumstances can result in subscribers overcommitting resources over time. If not properly managed, performance for all application workloads can be negatively affected. The following table provides an example of these key service settings, values, and justifications.
Table 15. Resource Allocation Settings Example – Committed Service Offering
Allocation Type | Value Range | Sample Setting | Justification |
CPU allocation | Variable (GHz) based on physical host capacity | 50GHz | The maximum amount of CPU available to the virtual machines running in the target organization virtual datacenter (taken from the supporting provider virtual datacenter) and the percentage of that resource guaranteed to be available to them. |
CPU resources guaranteed | 0–100% | 75% |
vCPU speed | 0–8GHz | 1GHz | This value defines what a virtual machine or vApp with one vCPU consumes at maximum when running within the target organization virtual datacenter. A virtual machine with two vCPUs consumes a maximum of twice this value. |
Memory allocation | Variable (MB) based on physical host capacity | 100GB | The maximum amount of memory available to the virtual machines running in the target organization virtual datacenter (taken from the supporting provider virtual datacenter) and the percentage of that resource guaranteed to be available to them. |
Memory resources guaranteed | 0–100% | 75% |
Maximum number of virtual machines | 1–Unlimited | Unlimited | A safeguard that allows control over the total number of vApps or virtual machines created by a subscriber within the target virtual datacenter. |
In this example, the CPU allocation setting serves as a block or aggregate limit for the entire target organization virtual datacenter and has been configured as 50GHz (50,000MHz). The CPU guarantee or reservation is dynamically changed as new virtual machines are powered on in the organization virtual datacenter. The value of the CPU guarantee is equal to the CPU resources guarantee (75%) multiplied by the vCPU speed (1GHz), multiplied by the number of powered on virtual machines, if this is less than the CPU allocation (50GHz) of the organization virtual datacenter.
The memory allocation setting also serves as a block, or aggregate, limit for the entire target organization virtual datacenter and has been configured as 100GB. The memory guarantee or reservation is dynamically changed as new virtual machines are powered on in the organization virtual datacenter. The value of the memory guarantee is equal to the memory resources guarantee (75%) multiplied by the memory of the powered on virtual machines, if this is less than the memory allocation (100GB) of the organization virtual datacenter.