It's time to rethink your data centre design
While many are familiar with the term “Catcher architecture” or “redundant block architecture”, few have put this model through its paces; although that’s about to change.
Today’s Data Centres are loaded with challenges – constantly working to provide maximum availability in the face of burgeoning demand, whilst offering continuous service and striving to always provide reliability and sustainability. These factors have become the performance baseline for every hardworking facility, all of which are also seeking significant savings in terms of CAPEX and OPEX for optimised electrical distribution – to be underpinned by the highest possible levels of resilience.
So how does architectural resiliency impact availability, and can intelligent design help solve some of the more troublesome challenges faced by Data Centres with an eye on their future performance?
Optimising Data Centre design with block redundant architecture distribution
Considering architecture strategy from a design perspective, the provision of a continuous, reliable service and the elimination of downtime are key – with availability rooted in architectural resiliency and the optimisation of TCO. Looking further ahead, CAPEX and OPEX are critical, but so is carbon footprint – all of which are impacted by architectural choices. Similarly, how straightforward it is to maintain a facility will also be impacted by early design decisions – as ongoing maintenance can become unnecessarily complex as a result of unwise moves concerning electrical distribution architecture.
Resiliency has become a watchword when it comes to design – particularly in terms of embracing modular solutions, sizing for a facility’s needs today but with the ability to scale and flex over time.
Certain designs will minimise the need for redundant hardware and optimise resource utilisation – leading to the installation of less equipment, lower capital costs and a reduced carbon footprint, while simplifying maintenance.
One such architecture, Catcher, ticks every box.
How does Catcher fit with typical UPS topologies?
With traditional 2N redundancy, a Data Centre has twice the necessary quantity of each critical component to ensure that no single point of failure can disrupt overall operation. Even in the event of a component failure, the system continues to operate without interruption, for exceptional reliability.
To provide this assurance in the event of unplanned maintenance or unexpected faults, the electrical design needs all the electrical equipment – generators, inverters, UPS, switches – to be redundant, which means investing in twice as much equipment and requiring twice as much space.
Architectures are now evolving to reduce the initial CAPEX by ensuring a high level of redundancy via distributed redundancy or Catcher architecture.
Distributed architectures – such as 4N3 and 5N4 – optimise power redundancy by sharing it between different systems.
There is a degree of complexity, however, as the power distribution to IT racks uses a different bus bar per power stream which can be costly and can also complicate maintenance processes.
Taking the example of 4N3 architecture, the 4 systems are able to work at up to 75% of capacity in normal operation and in the event of one supply being lost, the three that remain are able to continue to supply the IT load.
Using block redundant – Catcher – architecture to reduce cost and increase resilience
The Catcher architecture effectively allows the end user to choose the redundancy level required in order to optimise CAPEX, while maintaining fault tolerance and the possibility of simultaneous maintenance. For example, an architecture might comprise 6 normal power streams which can be loaded up to 100%, thereby optimising the usage rate of a Data Centre, and 1 or 2 redundant power streams – ready to take the load in case of one or two failures.
The use of static transfer systems (STS) placed between the UPS and the load means that the critical load can be transferred from the “normal path” to the redundant path, which will “catch” online, providing a continuous power supply without disruption to the critical load.
"In normal operation, loads are supplied by the normal path. In the case of any problems or maintenance on the normal path, the STS will automatically transfer the load to the redundant path. This block redundant architecture philosophy provides a seamless transfer from the normal path to the Catcher.
Another option with Catcher is the combination of a Static Transfer Switch and an Automatic Transfer Switch. For example, one side of the IT customer’s load (side A) is connected to the STS and the other (side B) is connected to the ATS – each is connected to both normal and redundant paths. In the event of normal path failure, the STS will switch first, bringing in redundant blocks, and the ATS will follow, ensuring a seamless and simultaneous transition for the two paths.
In conclusion, A and B side of the IT racks will stay supplied keeping the servers redundancy”
Optimised electrical infrastructure, with better TCO & greater sustainability.
When calculating CAPEX and OPEX benefits for Data Centres, the complete electrical infrastructure should be considered - from the high voltage transformer to the IT load. Choosing the right redundancy (1 redundant block for X normal blocks) will generate significant savings in terms of CAPEX and OPEX versus a traditional architecture. For instance, a full power stream could be removed; a transformer, a genset, the distribution board, a UPS, the batteries – as well as all the associated maintenance operations.
“When you scale up to 10 data halls, for example, although STS equipment is required to connect the redundant block, it’s still less equipment overall: fewer transformers and gensets, fewer UPS, batteries – up to 30% less equipment in total. As example when we compare a one STS Catcher architecture versus a 2N design, we see a global CAPEX reduction of 42% and a reduction in footprint of 38%. The result is a highly optimised electrical infrastructure, enhanced TCO and greater sustainability, which makes it a compelling solution for colocation Data Centres.”
Validated in the factory and proven in the market, these systems have been put to the test by prominent players in key Data Centre applications and the list of success stories continues to grow worldwide.
The Catcher model can optimise redundancy while limiting investment costs. Being highly flexible, it is the ideal solution in terms of adapting to the very specific and evolving needs of Data Centres – empowering designers to create better Data Centres and making it time to rethink their designs to ensure that they’re fit for the future.
And having been successfully installed in the field for a number of years, several hundred MW of Catcher have proven the high reliability of STS products in demanding operating environments.”
