When considering what you need in a new data centre, it is very easy to lose sight of the bigger picture and get caught up in the minutiae. The resulting design can often end up being far from ideal, causing delays while it gets reworked or, worse still, significant long-term problems if it actually gets built. The good news is that keeping focused on the following five key questions will ensure that your data centre design is accurately specified right from the word go…
1. How many racks do you need and what are their dimensions?
The number of racks determines the fundamental white space requirement of the data centre. Typical IT racks are 600x1000mm (width x depth) and a 100sqm IT room can comfortably hold approximately 50 racks. Of course racks come in other sizes too, so by knowing the rack dimensions and number of racks required it is easy to estimate the white space required for your data centre.
2. What Tier rating do you need?
The Tier rating determines the redundancy requirements and the power distribution paths. For a Tier 2 data centre, N+1 power and cooling capacity is sufficient. However, for a Tier 3 facility you will typically include N+1 cooling redundancy, 2N power redundancy with dual power feed, and separate A and B power distribution to the racks. Hence, knowing the Tier level determines the redundancies you need to design for.
3. What is the average power density per rack?
It is important to note that when you design the power capacity of the data centre, it should be based on the average power density and not on the maximum power ratings. The average power density multiplied by the number of racks gives you the maximum IT load of your data centre. This then drives the sizing of the active power systems, cooling system and incoming MLVDB/switch gear sizing. To avoid the pitfalls of an expensive and under utilised power system, a modular strategy is advisable to enable a data centre to be right-sized for both power and white space – minimising cost without having to sacrifice future agility.
4. Will you have AC or DC racks and what level of battery backup do you need?
The power requirement of the server racks can be 100 per cent DC, 100 per cent AC or a combination of both AC and DC power. For example, if you’re building the data centre for colocation purposes, you are likely to have an all AC (UPS) power requirement, while if it is going to be a telecom facility it will more likely need DC power. Knowing the answer will inform the sizing of the DC or UPS system required.
As for battery backup, it is advisable to dimension it based on 15 minutes autonomy per leg. Dimensioning battery backup for any longer than that will result in significantly increased capital expenses – something that would be very hard to justify when it would be much more cost effective to increase genset redundancy than to waste money on increasing battery autonomy.
5. Where will the data centre be located?
It is important to analyse the climatic conditions at the location where the new data centre is going to be built. This will help to determine the most appropriate cooling solution – DX, chiller, free air cooling, indirect free air cooling, adiabatic cooling, etc. – in order for the facility to achieve its target PUE.
There are of course many other questions that need to be considered in the design of a new data centre. But our experience at Flexenclosure has shown us that starting the process with a focus on this fundamental set of five key points will ensure that the resulting design comes as close as possible to what you really need.
(Srikanth Murugan is Global Director Sales Engineering at Flexenclosure).
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