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Are Blade Servers Right For You? Blade servers are finally getting the marketing buzz they deserve. Blades provide an excellent method to cram more into less space, and they also allow for more effective management of hardware. This article will explain some of the benefits of blade servers by looking at what types of features are available, and briefly touch on the difference between the big four vendors’ offerings.
Features What is a blade server, you ask? A standard rack will allow 42U (units) of space, which means that you can install 42 1U servers per rack. Assuming you have the power and cooling capacity, that is. A blade server starts with a chassis, which normally provides power and cooling for all the servers that will be inserted. Which components will live on which part (chassis vs. each blade) is dependent on the manufacturer, though, and it does vary wildly. For example, if a 42U rack can house six 7U chassis that each contains 14 slots for servers, an 82-server density is possible. Some configurations, especially with taller racks, allow for 100+ servers each. The capacity increase is enough to sell many people on buying a blade server, but there are other important benefits to converting. Depending on the manufacturer, of course, there are many features that accommodate ease of management. Most blade servers integrate the standard components of servers: networking, KVM, and power and cooling. Determining what level of integration actually was implemented is a per-server and per-vendor challenge. In the networking department, most blade servers have optional gigabit and fiber channel switch modules. Only one (or more for redundancy or throughput) connection is required per-chassis if the particular chassis supports networking. Similarly, an entire blade server consisting of 14 servers can connect to a SAN with only two fabric ports being used. On the power and cooling front, many blade servers use two 2000W (or higher) power supplies. Many of these require 3-phase 240V power, which is an implementation consideration for datacenters that don’t have this type of power. The advantage is that 3-phase power operates much more efficiently. You can power a full chassis of server with much less power than is required to run 14 1U servers, due to many factors. The cooling is also centralized per-chassis, so less power is consumed turning high-speed fans within each server. The Players IBM is the blade server market leader, currently offering IBM BladeCenter servers in three varieties. IBM’s approach is to implement power and cooling in the chassis, and each server is a distinct real-life server complete with CPU, RAM, and hard drives. With the optional fiber channel or gigabit network blades, networking can be consolidated. IBM offers two different blade chassis that are quite similar. The standard BladeCenter allows 14 blades, which can be mixed-and-matched IBM POWER or AMD Opteron servers. The two similar BladeCenter servers from IBM differ in that one is mid-range and the other, called the BladeCenter H Chassis is more geared toward enterprise operations. The H provides beefier power supplies and adds Infiniband capabilities. Both are quite suitable for high-performance computing, business applications, and database applications. The third, BladeCenter T-series chassis, is specifically designed for telecommunications applications. HP offers an interesting blade server as well, that accepts various HP ProLiant servers of Intel Xeon and AMD Opteron varieties. The HP p-Class BladeSystem has a few different options available for power: both a 1U and 3U additional chassis that allows customers to select their desired capacity. An optional Cisco gigabit Ethernet cards provides real switch functionality on-chassis. This is a middleweight blade server that’s sufficient for servicing most business applications. Dell also offers a we-want-to-play-too blade server. The PowerEdge 1955 is a blade chassis that accepts 10 servers in a 7U footprint. Each blade can be a 2-proc Intel Xeon server, with potentially 146GB of storage. Their website lists a host of market focuses, each with a “1” next to it. Selecting E-business, database, high-performance computing, or web services all lead to the 1955 server, indicating Dell claims it’s suitable for all applications. Egenera, however, is a breath of fresh air. Both their ES and EX line of blade servers provide a virtualized computing environment. The ES is designed for more light-weight applications, while the EX is ready to take on the most daunting computational loads. Of course, networking and storage (SAN) access is handled in the same way. Each blade in the Egenera chassis becomes a pool of resources that every operating system can access. The pool is called a Processing Area Network (PAN), and operating systems aren’t even aware it exists. The control blades virtualize everything, allowing multiple operating systems to run concurrently, and share resources in the PAN. Since the processors themselves are virtualized, you can mix and match Opteron and Xeon boards, and pull them at any time for maintenance while the system is running. Linux, Windows, and Solaris 10 are all supported. Egenera is certainly taking blade server in a new direction; one that provides some amazing flexibility never before seen. Why Blade Servers, Anyway? Total cost of ownership, return on investment, etc, etc. But the reality is that blade servers really do save tremendous amounts of space, power, and administrative time dealing with hardware. In the case of the traditional blade server, where one operating system runs on each blade, you aren’t saving anything in terms of configuration maintenance, because the same number of operating systems need to be tended to. The management advantage is realized when the same number of administrators can easily handle twice as many servers as they did previously, because less time is spent dealing with hardware issues. As virtualization, or all types, becomes more prevalent, hopefully more vendors will start making blade servers that provide a virtual server environment. The additional flexibility gained from a virtualized architecture enables IT organizations to approach today’s marketing claims of the traditional blade systems. |