Density for the Data Center

As demands for processing power increase, manufacturers are developing ways to pack more power into smaller spaces.

It was only a few years ago that the mantra was, "Consolidate!" Now, with the use of load-balanced server farms for Web traffic, and clustering for database servers increasing to handle the ever-expanding Web, the number of servers is growing faster than ever. After a while, it gets to be hard to find room for them all. Rack-mount servers have decreased in size from five rack-mount units (5 by 1.75 inches, or 5U) down to one unit, less than 2 inches in height. That means that a standard 7-foot rack will hold 42 servers. This seems like a lot, until you realize that a large data center might have hundreds or even thousands of these boxes.

We saw a bunch of ideas for increasing server density at N+I recently. What follows are three such approaches.

Putting multiple servers in a single box is not a new concept. One of the best-known vendors in this space is Cubix ( Each server is on a separate blade in a passive backplane system, which consolidates I/O. All three systems covered here offer variations on this theme, albeit with substantial differences.

The SlotServer from Omnicluster ( is a low-power server on a PCI card that can be inserted into a standard PC server chassis. The SlotServer cards use the host PC for storage, using the PCI bus to communicate between SlotServers in a cluster as well as to access storage. That means that a single rack-mount server actually can be five or six servers, with very high-speed interconnects between servers. Each card has a 10/100 Ethernet interface, USB and video port, and an IDE controller, which means that each SlotServer can have a separate disk if desired.

The SuperScaler 600 from e-Appliance Corp. ( essentially combines four 4.5-inch wide, 1U servers into a single one-unit rack-mount box. Each module is self-contained, with processor, memory, disk, power supply and three 10/100 Ethernet ports in a hot-swap design. A mail server, for instance, could be started with a chassis and a single blade, and more blades can be added as the need for capacity increases, without ever stopping the original server.

The RLX Technologies System 324 (www. offers the greatest number of servers in a small space of anything available to date. A single 3U system can contain up to 24 separate servers. Each server has a 633MHz Transmeta Crusoe processor, up to 512MB RAM, one or two hard disks, three 10/100 Ethernet controllers and a serial port. Because of its lower power requirements, all 24 cards run on a single 450-watt power supply, and there are two in the chassis, providing full redundancy. Another unique feature with the RLX system is that the first blade in the chas-sis can be configured as required, and then its configuration can be propagated automatically across the other blades in the chassis.

ISPs, ASPs, integrators and network managers should investigate all of these technologies—they can be substantially cheaper than multiple independent units, as well as easier to manage.