Data center trends: increasing power density

January 14, 2020
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Data center trends: increasing power density

At the data center design level, an important trend is to improve power density. In view of the space constraints of the data center, it needs to operate more efficiently to cope with the rising power demand and cost. Obviously, investing more resources in each rack is a very practical solution. However, in addition to its inherent benefits, increasing power density also brings some problems and challenges that must be solved for some data center operators.

Data center trends: increasing power density

Trend of power density

Low power density is often equated with low efficiency. Such valuable space resources are only consumed by so few IT equipment resources, and it also needs to consume more equipment maintenance costs. Ben kuglin, CFO and co-founder of colovore, a Santa Clara based high-density hosting provider, points out: "At present, the racks deployed by customers of typical data centers are about 8-12 kW per rack. Although the density requirements of some data centers are higher, the phenomenon of nearly 20 + kW is still rare for most intensive applications for big data analysis and processing. At the same time, there are still typical data centers in some coastal areas in the United States The frame is 4 – 5 kW (which was revised 10 years ago). "
In the managed space, the cost of supporting only low power density is very expensive, because the fully rented rack space may not be used due to the lack of sufficient power supply. Although a large number of equipment are equipped on the rack, the infrastructure supporting capacity of the managed space does not match. "Customers can easily deploy 8-10kw per rack on their existing server infrastructure, but because most data centers are designed to support only 4-5kw, they must implement half rack equipment operation across racks, otherwise they can't implement cooling well. But customers have paid for the whole rack, even though they only use half rack Load resources. This is undoubtedly a waste. "

One of the most obvious constraints on power density is the distribution infrastructure. Both the power supply provided by the utility and the level of backup facilities in the data center will affect the power density. For each watt of power provided by the utility, the data center must have enough ups and diesel generators to maintain its operation capacity in case of power failure. Of course, Cabling, power distribution units (PDUs) and so on provide power to special racks. Kuegelin pointed out that "most data centers do not have much power to supply their facilities, so they hope to obtain more power resources from public power companies and expand their core infrastructure (Electrical and mechanical infrastructure, generators, power distribution equipment, etc.) in the data center It costs a lot of money. Therefore, getting more power and cost are two important variables for the data center. "

But perhaps the more urgent need facing the data center is cooling: every watt of power consumed by the equipment will produce one watt of waste heat, which must be removed to maintain the operating temperature required by the data center. This is also the biggest challenge that the data center hopes to avoid when it does not intend to place the equipment at a higher density at first. "As you increase the density at the rack level of your data center, the servers will inevitably generate more heat, so more cooling is also necessary," kuglin said. "Cooling infrastructure is very expensive, but the biggest challenge may come from trying to transform old data centers. Most of these old data centers have low roofs at the initial stage of construction. In many cases, there is no simple way to improve the density. There are few methods other than demolition, but it is very difficult for data centers, especially when When it still hosts some customers. "

Unfortunately, for traditional data center enterprises, transforming their data center into a data center with higher density means that their data center facilities have little practical potential to continue to expand computing power except waiting for the improvement brought by semiconductor Moore's law. However, this method requires the purchase of new IT equipment, better process technology, and With the continuous progress of Moore's law, higher efficiency can be achieved, which may take about a decade. Kuglin points out that in this case, "Hosting providers can only simply use 'distributed load' or force customers to use their infrastructure across half a rack. However, this is obviously unsustainable. They will eventually run out of space, power and cooling resources as the client servers refresh."
Consolidated infrastructure drives greater power density

The promotion to higher density can be summarized as long-term infrastructure integration: basically, packaging more computer resources into smaller volumes can be realized through the existing trends in the data center, such as the adoption of virtualization technology, blade servers and micro servers. The integration of infrastructure "plays a very positive role in the operational efficiency of the data center," kuglin said, "Because the physical size of it deployment is smaller, the management authority of IT managers is more limited. When the number of servers is reduced by 30-50%, the savings in total power will be more meaningful."

This approach aims to reduce the total power of the data center by increasing power at the rack level (it has a dual benefit because it also reduces cooling requirements). "In fact, the power demand of each server has greatly increased, but overall, the total power can be reduced because fewer servers are required. This is why high-density data centers have become so important. They are the key to the integration of all infrastructure. Today's servers can easily achieve 500 watts to 1 watt per rack unit Kilowatts! "

Heat dissipation caused by high density

Of course, higher efficiency can be achieved through high density. Each rack houses as many equipment as possible, so as to help the data center save cost, floor space and solve management problems as much as possible. But the good things need to be weighed: in this case, it will cause cooling problems. Low density deployment usually adopts air cooling, and in most areas However, with the increase of power density in the data center, air cooling becomes prohibitive and expensive.
Compared with the evenly distributed direct cooling source, the solution of heat generation is more similar to providing point source: the heat generation is due to the level of rack, server and even processor. "The processing capacity of server chip level seems to be increasing continuously, but at some time, they will need internal cooling and implement cooling near the server immediately to prevent too much heat increase." Therefore, air cooling for only one point may still not be enough. Water resources (or other liquids) need to be used to provide greater cooling capacity. However, it needs to sacrifice part of the infrastructure delivery capacity, and there are some difficulties in improving implementation, such as strict isolation of cooling water from equipment electronic components.
Deploying a water-based cooling solution may cause some problems, especially for old data centers, and the existing infrastructure must be transformed. However, for new facilities that can support increasing power density, the water-based cooling solution can deliver the cooling capacity wherever needed, rather than just trying to keep the whole room stable The temperature is low enough to ensure the overall operating temperature of the server space. Schemes such as hot channel / cold channel can give the cooling air some room for maneuver, but this scheme also has its limitations. Finally, with the continuous improvement of the high-density requirements of the data center, soaking technology may become a necessary technology. Now some companies are providing products and packages in this regard It includes non-conductive fluid and the input of cooling fluid into the server chassis.
High density returns
For customers, whether they are managed service customers or data center operators, high density can provide them with important and lucrative returns in terms of total cost of ownership (TCO). Kuglin said, "When a company can consolidate its IT infrastructure to virtualized blade servers, it can immediately save more than 20% to 30% of its operating costs and 4-5kw of legacy deployment per rack. This is largely due to the saving of the power cost required to accommodate servers in the monthly cabinet and the reduction of the cost of cross connection and top rack switches." For managed service customers and data center operators, this means further expanding the available space of existing racks, showing off the trouble and cost of building a new data center, and its benefits are not just direct cost savings.
For those enterprises that want to maintain their old data center buildings or take the hosting route, with the rise of energy prices and the growth of IT service demand, they need to improve efficiency and save ground and rack space. Therefore, the implementation of high-density power in data centers is a major trend, but it is also a challenge: packaging more capacity into racks needs to be built The power distribution equipment, backup infrastructure and cooling capacity also need to provide relevant deployment support to maintain the management operating temperature. Although the method of coolant may not be a more common trend at present, it will become more common as the air cooling method gradually becomes less practical and affordable in high-density environment. However, whether from excessive air cooling to How long does the liquid cooling method take, and the power density of the data center will undoubtedly continue to rise, as enterprises are trying to maximize their resources.