Virtual Containment

March 2, 2015

An innovative step towards a more sustainable datacentre

This paper introduces the concept of partial & virtual containment, and how many Data Centres are now using this to improve energy efficiency and cooling effectiveness at a fraction of the cost & with fewer headaches in implementation when compared to full containment.

Data centres are mission-critical facilities and pivotal to successful business operations.

Surging demand for processing power, work load virtualisation and consolidation, combined with pressure to reduce operating expenses and improve asset utilization are making the thermal management of data centres even more challenging. With the combination of UK Government incentives supporting energy initiatives, upward spiralling energy costs and a tighter economy, never have our industry leaders been applying such pressure to the datacentre manager to review energy costs. Whilst cooling is widely acknowledged as the largest energy consumer- behind the IT equipment itself, airflow management is an essential component to the cooling strategy and managed well can contribute greatly to energy savings targets.

Thermal issues that were once ignored now must be addressed to reduce cost and increase potential capacity (releasing stranded capacity):

  • Mixing of hot and cold air – results in a loss of cooling effectiveness
  • Leakage – unintended hot / cold airflow paths
  • Hot air recirculation – exhaust is pulled back into equipment inlets
  • Airflow obstructions – increased resistance to IT equipment fan airflow

Data centre operators typically respond to these thermal issues in one or more of the following ways:

  • Lower the supply air temperature set point on the cooling equipment
  • Oversupply cool air by increasing the cooling equipment fan speed, increasing the amount of bypass air
  • Run more cooling equipment than necessary, underutilising available cooling capacity
  • Oversize the cooling system to address isolated high-density regions

These approaches to solving thermal issues lead to inefficiency and under-utilisation of available cooling resources in the data centre.

Containing the airflow of an entire aisle has been widely accepted to improve cooling capacity and energy efficiency by reducing bypass airflow. Many legacy airflow panels supply air in a vertical plume requiring the use of physical containment systems to reduce bypass airflow and improve capacity and efficiency.

W1

Benefits of Physical Containment

    • Significantly reduces bypass airflow
    • Customisable products and sizes for any retrofit application
    • Can achieve 99% capture index(CI*) at the server

* Capture Index is defined as the amount of useful cool supply-air captured at the front of rack supplying the IT Equipment.

Nonetheless, containment is not confined to just aisle doors and roof. In-rack containment in the form of blanking panels & floor grommets to cable access holes are most frequently an oversight, often the cause of much recirculated air flow from the hot exhaust of the IT equipment re-entering the cold aisle supply air path via gaps between equipment in the rack, and retrospectively, bypass cold air directed straight in the hot aisle from beneath the IT Equipment.

When varying rack heights prevail, the full containment solution becomes much more difficult and expensive to retrofit. Vertical Filler panels have been a solution to block up the subsequent holes, eradicating recirculated & bypass airflow, but are a costly add-on. Ventilation from the top of some cabinet types should also be noted e.g. EMC arrays. To add to these problems, customer change service requests may require racks to be removed from rows whilst other adjacent services need to be maintained; a clear benefit to the partial or virtual containment solution..

Virtual containment uses a set of solutions to deliver the right amount of air when it’s needed directly to the IT equipment. This is accomplished using directional airflow panels & control devices, or dampers, and doors at the end of the aisle to significantly reduce bypass and recirculated air, effectively providing containment without the need for a roof.

W2

Benefits of Virtual Containment

    • Significant cost savings over other containment strategies (no roof)
    • Comparable cooling capacity to full physical containment – achieves > 90% airflow capture index at the server
    • No fire suppression, lighting or service modifications required
    • Easily adaptable & re-useable to a changing environment

Used as part of a deployment strategy to manage the most from your current infrastructure assets, directional grilles and partial or virtual containment will mean that sequential energy savings are achievable, maximising return on investment and maintaining operational flexibility.

To conclude, each and every different data centre environment require individual address, and whilst Hot or Cold aisle containment may be suited for one environment, a virtual (or partial) containment solution may offer a very effective step toward significantly increased cooling effectiveness & energy savings for another.

As stated in the The EU Code of Conduct on Data Centres below, the implementation of Virtual or Partial Containment is an enabler to minimise bypass airflow which will then allow for reduced energy costs in cooling this air:

“The objective of air flow management is to minimise bypass air, which returns to the cooling (CRAC /CRAH) units without performing cooling and the resultant recirculation and mixing of cool and hot air increasing equipment intake temperatures. To compensate, cooling unit air supply temperatures are frequently reduced or air flow volumes increased, which has an energy penalty. Addressing these issues will deliver more uniform equipment inlet temperatures and allow set points to be increased (with the associated energy savings) without the risk of equipment overheating. Implementation of air management actions alone does not result in an energy saving – they are enablers which need to be tackled before set points can be raised.” (2014 Best Practices, The EU Code of Conduct on Data Centres V5.1.1).