What are Service Units?
A Service Unit (SU) is a measure of the cost of using Nectar compute resources. Each Nectar flavor has an associated SU-per-hour cost, as set out in the Nectar Flavors article.
Pre-defined Resource Bundles (Standard, Powerful, Extreme) come with a specified number of SUs. If you select the Custom Resource Bundle you will need to decide how many SUs to request.
Methodology: There is an internal formula used to convert the flavor attributes (VCPUs, CPU priorities, RAM and so on) to a base SU cost per hour for each flavor. The base cost is then adjusted for various reasons. For example, the costs of the deprecated flavors (including m1, m2) are weighted to encourage users to migrate to newer flavors.
Currently, we only assign an SU cost to explicit computational resources. In the future, we may extend this model to resources such as load balancers and databases that have associated implicit compute resources.
Note: When instances are shut down or suspended, they still continue consuming SUs. Only when an instance is shelved or deleted, then it will stop consuming SUs.
Requesting a Service Unit Budget
Each allocation will have a Service Unit Budget. If you are using a pre-defined Resource Bundle, then you do not need to worry about specifying this, as it is pre-selected for you. If you select the Custom Resource Bundle you will need to specify your Service Unit Budget.
The Service Unit Budget is the number of Service Units that can be used by the project in its current allocation period; i.e. from the start date to the end date. If you select the Custom Resource Bundle, your allocation’s Service Unit Budget is requested on the Allocation Request form, and is subject to review and approval by the allocation approvers. When you complete the information on your Custom Resource Bundle request form, you will need to estimate how many SUs you require.
Notes about the Service Unit Budgets:
The pre-selected Service Unit Budget in each of the defined Resource Bundles (Standard, Powerful, Extreme) is listed in the Resource Bundles Table. The Custom Resource Bundle is initialised with a Service Unit Budget of 16 000 SUs, but this can be increased or changed.
Unused Service Units do not “carry over” to the next allocation period.
If you consume 100% of your Service Unit Budget before the end of the allocation period, the project expiration process starts, just as if you had reached the end of your allocation period.
If your project’s budget will be consumed before the end of the project allocation period, you can submit an “early” request to renew. The Approvers will make a judgment as to whether or not to grant your request based on the circumstances, and on resource demand from other Nectar projects.
