Intel Atom processors vs. Intel Xeon processors for server clusters

When it comes to server processors, bigger and faster isn’t always better. Linux Magazine has published an article about how using less powerful processors (but more of them) can actually be a smarter decision than using top-of-the-line CPUs.

The author of the article, Douglas Eadline, compares building a cluster with Intel Xeon processors to creating one with Intel Atom CPUs. The Xeon is more powerful and more expensive than the Atom, but requires substantially more power.

Eadline calculates the advantages of building with one processor over another. The Price of one Xeon/Price of one Atom ratio is 22 while the Performance of one Xeon/Performance of one Atom ratio is only 7.7. That means that, while you may pay 22 times more for a Xeon than an Atom processor, you are only getting 7 times the performance of the lesser expensive CPU. This comparison suggests that, based on these parameters alone, buying servers with  Atoms may be a better choice than purchasing systems with Xeons.

But the matter is not so simple. While each Atom processor draws drastically lower quantities of power than a Xeon processor, these savings are negligible when one looks at the bigger picture. The Thermal Design Power (TDP)/Performance ratios of the processors, Eadline calculates, are about equal, meaning the two processors do not differ much in terms of power consumption.

Also, Eadline observes that while you may get better performance for every dollar with an Atom than a Xeon, this only holds true when comparing strictly processor prices. But, a cluster with Atoms will typically have more motherboards and memory DIMMs than an equally-powerful cluster with Xeon processors. To calculate whether Atoms are really a better deal than Xeons, one has also has to figure in the cost of those extra pieces of hardware.

In addition, some server functions are better performed by Atom processors than others. The Web hosting industry, which does not run large databases or complex modelling software, typically only needs to store and access web pages, a relatively simple function. Clusters with Intel Atom processors are well-suited for such functions. SeaMicro, a manufacturer of large server units, has built a 10U server system with 512 Atom processors that only consumes as much power as four desktop computers, reports ServerWatch.com. The individual Atom systems, which have smaller motherboards, were re-engineered to have a compact design which is not possible to achieve with clusters running more powerful processors.

So Atom clusters may be a viable solution for individuals or companies whose servers do simple functions. Even then, one must compare a variety of factors to determine whether “cheap in quantity” over “expensive with quality” is the wiser way to go. In any case, Atom clusters are definitely an option to be considered, especially for hosting companies.