All4Green will design new flexible contracts between ICT users and data centres, revolving around the use of Green-SLAs to enable new energy saving policies that can be tailored to different computing styles and can be used with all data centre monitoring and automation frameworks. In addition, matching energy demand patterns of data centres and the energy production/supply patterns of the energy producers/providers will enable peak shaving, the reduction of inefficiencies in energy production, and the exploitation of renewable energy sources without endangering the stability of the grid.
All4Green envisages energy savings derived from the synergistic effects of three new energy optimization directions, enabled by the comprehensive research scope of the project:
- Data centres offer services to ICT Users, respecting Service Level Agreements (SLAs) typically centred on performance and availability. In the proposed approach, Green-SLAs allow data centres to relax certain constraints (in a regulated way) to achieve high energy savings with minimal impact on the performance and availability of the system. One simple clarification example is the fine granularity definition of performance based on the effective request rate, allowing a drastic reduction of ICT resources during low load periods. All4Green Green-SLAs between data centres and ICT users will give also data centres the freedom to react to requests from the energy provider to temporarily reduce its energy consumption e.g. by temporarily putting low-priority jobs on hold or abstaining from some degrees of cooling.
Data centres are high energy consumers. Sharing mid-term (days) power need plans with the respective electrical power provider will allow the provider to align energy production and usage. Moreover the data centre, based on Power Provider requests, can contribute to short term (minutes) energy consumption reduction, to help handle power consumption peeks. The benefits for the data centre implied by this collaboration are the following:
- Reduced risk of power shortages, especially useful also when the power provider is using non constant power sources, like wind and sun.
- Reward the “collaborating” power consumers with economical reduced rates and incentives (indirectly these new economical model will allow the data centre to share the revenues with “collaborating” end users, i.e. the ones accepting Green-SLA)
While power providers will:
- Reduce extra spending for last minute energy buying on the marketplace.
- Reduce emissions due to the possibility – for the power provider - to lower the proportion of polluting energy sources, potentially even to zero.
- Reduce the need to use inefficient energy sources.
- Reduce the transport of energy from production locations far away from the consumption area, therefore avoiding the energy loss/inefficiencies of the transportation.
- Data centres can federate and collaborate to exchange load among them, to meet short time power reduction request from power users, and also to collaboratively develop medium term plans that capitalize on the price and quality attributes of the energy offered by different power providers. In this scenario a federation is a set of separately managed data centres, with collaborative attitude governed by dynamic negotiations.
Optimizing these three collaboration dimensions in an integrated way in one ecosystem leads to a situation where it is not the energy provider alone who is responsible for detecting and reacting to peak energy demands or a sudden supply of renewable energy. Instead the energy provider triggers a reaction chain that starts with its request to the data centre to lower power consumption. The data centre quickly replies to this request by applying a set of mechanisms that temporarily reduces its energy demand.
- Some of these mechanisms focus on the temporary reduction of work load on the data centre infrastructure by delaying jobs (time shift) or relocating jobs to federated data centres (location shift). These actions require cooperation between data centres and their customers. This cooperation can be achieved by the design of Green-SLAs that create an incentive for the data centre customer to accept temporary compromises in traditional KPIs.
- Other mechanisms that the data centre can apply rely on the principle of building up energy reserves that in times of shortage can be used instead of energy from the public electricity grid. The data centre can either store this energy directly in a UPS or it can it thermally by reducing the temperature in the data centre beyond what than necessary, for instance in times when a surplus of renewable energy is available. Moreover, thermal “debts” can be created by allowing the temperature to rise up to a certain extent – these debts can then be paid back with renewable energy.