Since rack servers operate in very close proximity to one another, they require more active cooling than tower servers do. The fans in these servers can be quite loud, and you’ll need a climate-control system to keep a full rack cool. For those reasons, most businesses isolate their rack servers in a dedicated room. Rack servers can be more difficult to maintain, because they must be physically pulled from the rack for servicing. And like a tower server, rack servers require a KVM arrangement for setup and management.
An entry-level rack server in Lenovo’s ThinkServer RD230 line includes a dual-core Intel Xeon E5503 CPU; four 3.5-inch hard-drive bays, with support for RAID 0, 1, 5, and 10 (no drives are included); and 2GB of memory (with seven additional slots for expansion) in a 1U enclosure. It sells for about $1,000.
Prices escalate quickly as you add CPUs (or CPU cores), memory, hard-drive bays, virtualisation capabilities, and other features. When you compare the prices of rack servers, be sure to include the cost of an operating system and any embedded hypervisor (for virtualisation) that you might want, as these elements are not always included in the base price. You should also consider the price of the rack and the mounting rails you’ll need to install the server.
The primary distinction between a rack server and a blade server is that several blade servers operate inside a chassis. Adding a new server is as simple as sliding a new blade into the chassis. You can install other network components, such as ethernet switches, firewalls, and load balancers, alongside the servers in the same enclosure, and you can install the whole assembly in a rack. Since the chassis provides the power, cooling, input-output, and connectivity for all the devices inside it, you don’t have to deal with new cables when you add something. Blades are neater and can pack more computer power into a given space than any other server ecosystem, yet their upfront cost is higher because you must also purchase the enclosure.
Blade servers do have their drawbacks. Typically they provide fewer expansion opportunities because they aren’t equipped with as many PCIe slots and drive bays as tower or rack servers are. On the other hand, businesses deploying blade servers usually have shared storage, such as a storage area network, to support their blade servers (and some blade chassis can accommodate SAN storage right alongside the servers). As you’ve probably guessed, housing all those components in such close proximity generates a lot of heat. Blade systems, like rack servers, require plenty of active cooling (usually augmented by fans mounted inside the chassis).
The bottom line
If all you’re looking for in a server is file sharing, client backup, and limited remote-access capabilities for a small number of employees using computers (10 or fewer), a Windows Home Server machine or a NAS will satisfy your requirements with an extremely modest investment. A larger small business that needs just one or two more-powerful servers would be better off with towers. They don’t take up a lot of floor space, and they don’t require elaborate cooling systems, but they’re easily expanded, and high-end models can support virtualisation.
Once your IT requirements grow beyond what a couple of servers can do, it’s time to consider moving up to a rack server. Dozens of these machines can fit in the same footprint as a couple of towers, and this server architecture is quite scalable. Blade servers are even more space-efficient and scalable. If you need more servers than will fit in a rack, you’ll be happier with a blade ecosystem.
An entry-level IBM BladeCenter S chassis, which can accommodate up to six one- or two-processor blade servers (or up to three four-processor models) and provides two disk modules and four switch modules, costs about $2,700. An IBM BladeCenter HX5 server equipped with an Intel Xeon CPU, 16GB of memory, and two hot-swap disk bays (drives not included) is priced at $6,227. As with the other types of servers I’ve discussed, list prices don’t include an operating system or virtualisation capabilities, and prices climb rapidly as you add features and components.