The making of energy efficient datacenters

The Crooked E: The Unshredded Truth About Enron is a wonderful movie to watch. It is based on the book, The anatomy of greed, written by a former employee of Enron, Brian Cruver.  One interesting thing that comes on our minds is the size of all power companies. They are all huge. We all depend on power for just about everything and yet very rarely do we think about conserving energy. A typical PC for example takes about 135 watts of power. A data center with about a 1000 servers should typically take about 135 x 1000 Watts or 135 Kilowatts and that would just power the computers. This does not include the air-conditioning and lighting. According to to a research paper sponsored by The California Energy Commission in a datacenter about 50% of the total energy consumed is by the servers and  about 35% is the air conditioners.


Here are some interesting research done in this field –

  • Feeling the heat– An interesting paper by Liebert describing the challenge of effectively managing the heat dissipation in datacenters.

This problem can be solved by making better energy efficient air conditioners and by making more energy efficient computers. Many companies have taken a lot of interest in subject. However, nothing substantial has been done primarily because of the market requirements. The end users still want to host their sites on the fastest processors which drives the market with the latest processors. Going at this rate we would reach a time soon when the energy required would be much higher than the energy available in the market.

Intel, AMD, Transmeta and Via have all released processors which consume very low power. A typical Pentium or AMD processor consumes about 25 Watts of power, whereas these low powered processors take only about 5 watts of power i.e. about 5 low powered processors would consume as much power as a single main stream processor of today. These low powered processors are also generally fan less processors which means lower noise levels too. Intel has the centrino which has a lower power consumption than the regular pentiums. Intel also has the arm processors but those are RISC. Our prime focus would be AMD, Transmeta and Via. They all have some very promising products.

One thing to be noted is that most of these low powered processors work only at about 1.2GHz or lower. So they won’t be as fast the pentium4s. Which means one would have to host lesser sites per server. A good recommendation would be  upto a maximum of  600 sites on a regular pentium 4 server. A low powered processor should comfortably take about 200 sites. One advantage of these low powered processors is that they have a very small form factor too. This means that one can have more such servers in the same space that is typically allocated to a high powered servers. All datacenters use a profitability matrix based on the following rule: Performance/Per Watt/Per Cubic Foot. This is one place where the low powered processors really score high.

 AMD Geode™ NX Processor family comprises of  the AMD Geode™ NX 1250@6W processor, the AMD Geode™ NX 1500@6W processor and the AMD Geode™ NX 1750@14W processor. The first two in these consume only 6Watts of power and run without a cooling fan. According to AMD they provide the highest x86 performance for fan less operations. They are based on the mobile AMD Athlon processor technology.

Transmeta was one of the first companies to develop low powered processors. For a long time Transmeta was known as the company where the Microsoft co founder Paul Allen had interests in and the place where Linus Trovalds, the father Linux, worked. Both of them are no longer part of the organization. Today they are known for the two processor families they have – The transmeta crusoe and the transmeta efficeon

Transmeta Crusoe™– processors range from 500Mhz to 1.2 Ghz. According to Transmeta, Crusoe is a unique combination of software and hardware. It’s this radical design that gives Crusoe its important advantages, and manufacturers of all kinds of electronic devices their first truly innovative new platform in over 25 years. Thanks to Crusoe, mobile devices can be made smaller and lighter than ever. These new devices will be more comfortable to use, too, because Crusoe generates very little heat a problem that plagues the industry’s legacy hardware-only processors. And because it uses far less power, mobile devices running on Crusoe run far longer on a single battery charge, and Crusoe-powered ultra-dense servers do far more work per watt, far more efficiently.

Transmeta Efficeon processors are the higher end processors from Transmeta and they run at upto 1.6Ghz and have high performance I/O interfaces. They are built upon Fujitsu’s next-generation 90nm silicon technology featuring transistors with a length of just 40nm.

The entire Transmeta range not just uses the x86 instruction set, they also have full multimedia instruction support (MMX, SSE-SSE2). Transmeta has done very little in marketing in terms of selling their products for the server market. Like all other companies they have focussed on mobile products, set-top boxes etc.. While these products are great for the mobile market, they do have a great potential in the server market. FIC, JM-Net etc. have some products for the server market which run on the Transmeta processors.

Via , the Taiwanese manufacturer purchased the Cyrix processors and has since gotten out of the race of faster processors with AMD and Intel. Instead they are focussing on fan less, low-powered processors. They have the Eden and the C3 range of processors. The power consumption varies from only 7watts  to 15Watts.  Additionally,  the processors come with  the PadLock Hardware Security Suite which provides a platform approach to computer security, ensuring uncompromising security performance. These features include the implementation of the Quantum-based VIA PadLock RNG (Random Number Generator), and the VIA PadLock ACE (Advanced Cryptography Engine) supporting AES encryption.

According to Via, the VIA Eden-N Processor is the world’s smallest, lowest power and most secure native x86 processor. It is a mere 15mm x 15mm in terms of size and consumes between 2.5W @ 533MHz  to 7W @ 1GHz. 

Via again like Transmeta has not focussed in the server market. The images above give a good idea of the benefits of this processor in the server market. For datacenters, Via may be the best in the Performance/Per Watt/Per Cubic Foot matrix.

Companies like Hitachi make some very good low powered hard disk drives which have a very small form factor. They have both IDE’s at 7200 rpm as well as SCSI hard drives.

Many may think it is better to take higher end servers as the power or heating problem does not directly affect them. As mentioned earlier a server driven by a low-powered processor would be able to take just about 200 sites. This means that a person with 600 sites would need to take 3 such servers instead of one higher powered server. Here are some benefits of this scenario.
One of the biggest factors influencing the performance of sites on the internet is the capability of the network card (ethernet) . When all sites are hosted on just one server, they all would use the same network card to push the data. Now if these sites are distributed among 3 servers the amount of data that the sites can push would be 3 times more which means faster access to the sites. Another benefit is that if one of the site goes down all 600 people would not be effected, rather only 1/3rd the number of sites would be affected. Hence, the number of support request would be lesser. And finally, such processors are very affordable. Typically they would be just a third of the cost of regular mainstream processors.


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