UPS is every data center’s necessity. Without it, you might just as well close shop and go home. A UPS is required for one of two reasons: to ensure power supply to the servers until you can switch to a secondary power source; in case you don’t have a secondary power source or the source is not in operation, they keep the servers running till you safely turn them off.
Data Center Talk has written extensively on UPS systems in the past. But the subject of UPS is like a bottomless well. People are plagued with unlimited questions. After all, no one wants to invest in a system that is not capable of handling the data center load. One of the major questions plaguing the minds of data center designers is whether to opt for modularised UPS system or to just centralize the system.
Allow me to make a pros and cons list for you.
Pros of Modular UPS systems:
- Capacity of the UPS systems can be increased when required. You will not have to buy a high capacity UPS and wait for your data center to add more servers to achieve full load conditions.
- Also, you have to keep in mind that if you constantly run your battery system at an underrated capacity, the backup time reduces drastically over time affecting the life of the UPS. A UPS system can achieve maximum efficiency only near its maximum rated capacity.
- Maintenance and repair related issues are easier when dealing with modular systems. With an N+1 configuration, it is no sweat at all. Localised troubleshooting will be a breeze.
- N+1 configuration is cheaper with modular systems too. Imagine the cost of the system if you decided to adopt N+1 with a centralised system. And have you thought about where would you store the additional unit?
- Modular systems reduce redundancy.
Cons of Modular UPS systems:
- The modules are usually installed near the servers or they tend to be placed in the server racks. That is added weight and space requirement in the machine room.
- Cooling requirements also rise drastically.
- Localised UPS system has a drawback. If a particular row is not making use of full load capacity of a UPS, it is hard to divert the power to another part of the floor where there is need.
- It is also unsafe to have batteries in the same room as the servers. They produce chemical by-products which can be corrosive in nature.
- Food for thought. The more number of components, the more chances of failure. Modular UPS systems inherently come with more components. Chances of system failure increases by that much. But most UPS systems these days come with a reliability tag attached to it. This point of argument might just not make a winning statement in itself anymore.
But you can always adopt a mixed strategy for UPS systems in case you have a large data center. You can choose a centralised UPS system for your primary power backup needs and you can back up the centralised systems with modular systems without spending a bomb on it.
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