Server form factors: A guide to rackmount, blade servers and more
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By Yuval Shavit, Features Writer
IT functions are getting more complex, and many businesses are struggling to keep up. Some of those businesses are starting to look toward blade servers as they try to consolidate computing power and keep costs low, but blades aren't for every company. Small and medium-sized businesses (SMBs) tend to be wary of blades, and many of those that do buy them stop after one rack. Blades aren't a panacea for growing computation costs, but they can be useful. This Hot Spot Tutorial will explain the main advantages and disadvantages of blade server technology so that you can help your customers get the most out of them -- and know when to avoid them altogether.
A blade server is essentially a stripped-down version of a standard rack-mounted server unit that contains just the bare essentials: a CPU, RAM, integrated I/O ports and network adapters. Other components, like power converters, cooling equipment and storage, are provided by the blade server chassis, which itself fits into a standard rack enclosure. Because blade servers don't have internal storage, your client will need shared storage, like network-attached storage (NAS) or (preferably) a storage area network (SAN).
The compact layout of blade server technology makes it possible to pack more units into each rack and consolidate several standard server racks into one blade server enclosure. Advocates of the technology say this lets companies free up much-needed server room space, although some systems integrators (SIs) have found that the space clients save with racks is taken up by the more complex cooling equipment that blades tend to require. Blade servers do make for tidier server rooms, though; blade server chassis consolidate power and networking cords, so there are fewer cables overall.
But buying into blades can be expensive. Although blade servers themselves are often cheaper than standard rack-mounted servers, the chassis is more expensive. If your client buys a blade chassis and populates half of its available slots, the overall cost per server will likely be greater than if the client had used standard servers instead, said Eric Nelson, director of business development of Alteritech Inc., an SI and managed service provider (MSP) in Vienna, Va. On the other hand, if your client needs enough servers to fill the blade chassis, the economies of scale will factor in and save the client money, Nelson said.
In determining whether the investment in blades would make sense for your customer, you can factor in some growth projections, but it's better to be conservative and focus on the near term, Nelson said. Blade server technology is evolving quickly, and what you buy now may be obsolete in a year. While that's true of any technology, it means that your customer should plan on filling any blade chassis it buys within 12 months, Nelson said. If your growth estimates for the customer don't project it filling the chassis within that time, it's better to just use standard servers for now and re-examine blades at the next refresh cycle.
Another major disadvantage to blade server technology is cooling. In theory, the overall cooling power your customer will need before and after buying blades should be about the same, if each old server is converted to a blade. It could even be lower, especially if you're using blades for server virtualization. But because blade servers are so much denser than standard rack-mounted units, they require a more sophisticated, and usually more expensive, approach to cooling.
Many SMBs buy blade servers only to discover that cooling them is too difficult, said Peter Sacco, president of PTS Data Center Solutions in Franklin, N.J. Those companies often give up and go back to buying standard servers, he said. Worse still, the cooling equipment blades require often eats away at the floor space they save, making the overall savings negligible, he said.
Despite the caveats, there are situations where blade servers make sense. Coupled with server virtualization, for example, blade servers can enable huge reductions in server hardware in the data center. In the next installment of our Hot Spot Tutorial, we'll look at the uses for blade servers and how to get the most out of your client's investment.