Five ways to cool the blade server

        There are five basic ways to dissipate a blade server. Once one of these methods is selected, it can be implemented in a variety of different products and methods. Table 1 summarizes this.

to blade server applications, where a method must be selected. This choice is based on the constraints of the current facility and the needs and preferences of the user.

Selection of application methods

Understanding the constraints of existing facilities and making appropriate trade-offs between users' various needs and preferences, they can be based on the five basics described above. The choice is made in the method. The choice of application methods for blade servers is based on thermal issues, as these are the most important constraints in real systems. After determining the application method, the power supply problem will be determined.

The most important factor affecting the way applications are the density of blade servers. Many users prefer to install blade servers at maximum density. This is often not an appropriate choice in an existing data center environment. In fact, most blade servers have a modular rack structure that can be installed in a cabinet at a lower density. For example, IBM BladeCenter uses a separate rack that can accommodate from 1 to 6 blades in a single cabinet. While reducing installation density does not seem to take full advantage of blade servers, the cost, availability, and installation speed of the system are actually improved, especially when installing blade servers in existing data center environments.

Many data centers today have power densities of 2 kW or less per cabinet. When installing blade servers at a power of 10-30 kW per cabinet in such an environment, these blade servers consume a lot of power and cooling, which is out of proportion with the original design of the equipment room. For this reason, there is usually no real benefit in saving space when installing a blade server in an existing data center. Therefore, it is both practical and cost-effective to distribute blade servers in existing data centers. Installing blade servers at saturation density is usually only a good deal in a new facility that is designed to support high-density solutions. — installation is extremely large or extremely small.

Therefore, the core choice for blade server installation is the degree of fragmentation of the blade server installation—how many blades are installed in each cabinet. The brand and model of the blade server chosen by the user may limit the degree of blade dispersion. For example, some blade servers use separate racks, which are easy to disperse. Other blade servers use a backplane system that makes distributed installation impractical. For a more comprehensive and detailed discussion of this issue, see the “APC Application Notes” associated with a specific blade server brand. After planning the application density of the blade server according to the five main blade server application methods described above, the results are shown in Table 2.

Table 2 shows that, in the 30 different combinations of power density and application methods, there are about 11 kinds of combinations of the preferred combination of critical and 7 - total 18 kinds of more practical use in combination . To choose the best solution, you must compare the data of thousands of users' preferences, constraints and existing conditions with these 18 application methods. This comparison requires extensive analysis and follows many rules, which can be done like software operations. However, it is not described in detail in this white paper.

In the process of developing this tool, we have come up with some key lessons from long-term observations in actual work:

If you need to install a blade in your room If the server cabinet exceeds 25% of the total number of cabinets, the power and cooling system of the existing data center may need to be fully modified. This means that if the number of installations reaches this limit, the user needs to rebuild a machine room, otherwise the data center must be shut down for a period of time to perform system transformation.

If an existing data center is planned to install 1 to 5 blade server enclosures, then to minimize the impact on the normal operation of the data center while reducing installation costs to 25% or 50% of the saturation density The number (for example, up to 3 racks in each cabinet) is most suitable for installation. For most data centers, the cost of achieving very high power densities is much higher than the space cost required to add several cabinet locations.

The current data center generally provides cooling and power supply for the whole system equipment. The auxiliary cooling solution can increase the application density at a lower cost while achieving predictable heat dissipation.

Inappropriate practices

The following are some of the methods and practices that data center managers often use, but these methods are flawed, they don’t help much, and they tend to The situation is even worse.

Reducing the air temperature. Users usually reduce the air temperature in the equipment room by lowering the temperature setting of the computer room air conditioner to solve some hot spots in the data center. This is the easiest and worst practice for user operations. Taking this approach will reduce the capacity of the air conditioning system, greatly increase the water consumption of the humidifier, and greatly reduce the efficiency of the data center (the result will also increase the electricity bill on your bill). All of this happens, and the problem is not solved at all, because it is a problem with airflow, not a problem with air temperature.

Floor grille. Another plausible measure is to replace the ventilated floor tiles with raised floors on the grille with larger air holes. This grille is not the familiar floor tile, but a bit like a stove. This approach can be helpful for isolated cabinets, but there are serious side effects – especially if such tiles are used in large quantities. The use of such tiles in data centers typically results in reduced airflow in other areas, but more importantly, these grids can cause significant unpredictable changes in airflow between the tiles. This issue is detailed in the APC White Paper 46 “The Heat Dissipation Strategy for Ultra High Density Cabinets and Blade Servers”.

The fan at the top of the cabinet. It is common to install fans on top of the cabinet - although these fans do not have the benefit of a well-designed IT cabinet. The reason for the server overheating is not the inside of the cabinet, but the hot air at the entrance to the front of the server. These fans can only generate more heat and even reduce the heat dissipation of a well-designed data center. Many users determine the fan's specifications according to traditional specifications if the purpose is not clear. There are also some effective fan-assisted devices for the cabinet, which are described in more detail in the APC White Paper 42 “Resolving the Ten Steps of Applying High-Density Servers to Heat Dissipation”.

Isolated cabinet. Sometimes the user will list the cabinet from the entire row of cabinets, trying to reduce the density of the cabinet within a certain range, so that the airflow of the ventilated floor tiles can reach the cabinet more. However, this method allows the hot air discharged from the equipment to flow back around the cabinet to the air inlet of the server. The overall effect is not very good. A better approach is to have the cabinet in a hot and cold aisle arrangement, separated by an unloaded cabinet with partitions between the blade server cabinets, widen the cold aisle, use auxiliary cooling and/or hot aisles Seal the system to enhance heat dissipation.

Conclusion

in pressure on existing data center power and cooling systems will application blade server data center, this pressure can not be ignored. There are several ways to provide power or cooling to a blade server. The best approach to a particular installation depends on the constraints of the existing design and the needs and preferences of the data center managers.

This article outlines issues and options related to blade server applications. The process of selecting an application method based on constraints of existing data centers and user requirements is also described.