1. Field of the Invention
The present application generally relates to cooling control apparatuses, and more particularly to a cooling control apparatus for controlling cooling of computer systems.
2. Description of the Related Art
Recently, computer systems are widely used and play important parts in various fields. Therefore, breakdown of a computer system may cause severe damages to our society. It is especially essential to realize stable operation of what is called server systems.
In order to achieve stable operation of server systems, it is necessary to assure that CPUs (Central Processing Units) work stably. Ambient temperature is one of factors which can affect stable operation of CPUs. Since CPUs can operate stably under relatively limited conditions, cooling control of the server systems is essential in view of improving system stability.
Conventional server systems usually operate for more than twelve hours in a day, and in addition, they are often set up in locations where many people pass by. Further, today's societies in the world are active for 24 hours. Therefore, systems must be designed from a viewpoint of unmanned operation under severe circumstances.
FIG. 1 is a diagram showing a CPU part of a conventional computer system. As shown in FIG.1, a plurality of CPUs 2-1 through 2-n are mounted on a circuit board 1. Fans 3-1 through 3-4 are mounted on the circuit board 1 for cooling the CPUs 2-1 through 2-n with fresh air.
The fans 3-1 through 3-4 are connected to a control device 4. The control device 4 monitors conditions of the fans 3-1 through 3-4 such as elapsed time or a total number of rotations since the fans were mounted. The control device 4 outputs a warning signal which indicates that the fans should be overhauled based on the monitored conditions and the life of the fans. The system administer can overhaul or replace a fan for which the warning signal has been output.
In the conventional cooling control apparatus, a fan for which the warning signal has been output is replaced even if the fan has sufficient cooling capability or the other fans can sufficiently cool the system. When a fan is replaced, operation of the system must be stopped. In addition, the conventional cooling control apparatus is so constructed that operation thereof is automatically stopped when a fan has failed even if other fans can perform sufficient cooling.
As described above, since the conventional cooling control apparatus monitors only an individual state of each of the fans, the computer system may be unnecessarily stopped due to replacement or failure of one of the fans. Thus, according to the conventional cooling control apparatus, computer systems cannot operate efficiently.