Understanding server form factors: A guide to rackmount and blade servers

As more data centers look to purchase new servers–often after long delays in refresh cycles–budget constraints and changing technologies mean purchasing decisions have become even more difficult. Sifting through the myriad of options and weighing the pros and cons of rackmount servers versus blade servers can complicate that decision. Today, IT professionals are taking a closer look at which servers are right for them and kicking an old trend of making purchasing decisions based on a previous relationship with the manufacturer. At a time when many shops are being asked to do more with less, it is now reliability and price that most influence a server purchasing decision. This guide to understanding server form factors can help cut through the hype and let IT professionals find the server that fits their budget and their needs.

Table of contents:

Rackmount servers: Traditional and larger form factors

While blade servers have gained popularity over the last several years, the traditional rackmount servers, such as 1U and 2U servers, remain the basic building blocks for today’s data center. IT professionals turn to these servers to handle a variety of workloads. There are countless models of rackmount servers available from various manufacturers, and the features and capabilities that those servers provide is just as diverse. Even within the same form factor, it isn’t uncommon to see wide ranges of processing power, memory and storage capacity, with each variation optimized for a particular use. We’ve assembled these tips to provide information to IT professionals who are looking to buy or learn more about rackmount servers.

Server features and functionality: An introduction
1U servers are powerful, economical and versatile, making them a great choice for almost any data center. While they aren’t always suitable for compute-hungry database applications, they are great for everyday business operations and even make good virtualization platforms. However, manufacturers and models vary significantly, and there are countless options to choose from. This tip provides an overview of 1U servers – explaining their pros and cons–and includes a side-by-side comparison of offerings from Dell Inc., Hewlett-Packard Co., Fujitsu and Super Micro Computer Inc. to evaluate their specs and capabilities.

Turning to 2U, 4U servers in virtualized data centers
Data centers managers looking for more computing power to improve virtualization performance often turn to 2U and 4U servers for their increased memory support and expansion capabilities. However, IT pros looking to purchase one of these larger form factors should consider whether it would really be able to meet their needs. Manufacturers of larger form factors typically take advantage of the extra room by adding more memory, storage or expansion slots, but features and capabilities between manufacturers vary dramatically. This tip includes an explanation of the features available in larger form factors and a side-by-side comparison of popular servers. IT pros who are looking to purchase a 2U or 4U server will find this tip an invaluable resource.

Blades vs. rack servers for virtualization
Deciding whether to use blade servers or rackmount servers for virtualization can be complicated. Even virtualization experts disagree on which form factor is better suited to host virtual machines. Some organizations find the benefits of blade servers–simpler management and efficient use of space–to outweigh the disadvantages in a virtualized environment. However, some IT professionals believe the lower initial cost of rackmount servers makes them a better choice. In this face-off, two IT professionals and virtualization architects offer differing views on which server form factor to use for virtualization.

Blade servers: Big on computing power, small in size

Blade servers have become an integral part of data centers, with 51% of respondents to our Data Center Decisions 2011 survey reporting that they are deployed in their data center. Blade servers give IT professionals the advantage of adding computing power to tackle demanding workloads without the bulk and cost of larger server form factors. Blade servers offer distinct advantages for some applications, including Web hosting and virtualization. But the very properties that make them attractive to IT pros also generate their own set of challenges. Since blade servers can be arranged to achieve much higher densities than standard rackmount servers, they often require a more focused–and usually more expensive–approach to cooling. In this guide, we highlight tips that describe specific advantages and disadvantages data center pros have seen when using blade servers for different workloads.

Blade servers: An introduction and overview
Understanding the features and capabilities of blade servers is the first step in determining whether to integrate blades into a data center. Unlike rackmount servers, blade servers do not include several key components, such as cooling fans and power supplies. However, they do provide a high level of computing power for a smaller price when compared to standard rackmount servers. This introduction and overview of blade servers can help IT professionals decide if blade servers will benefit their environment.

The benefits of blade enclosures for virtual server load balancing
Blade servers have gone through many changes since they were first introduced. Optimizing them for virtualization is one of the most important changes the blade form factor has seen over the years. Limitations that once made blades a bad choice for virtualization, such as I/O bottlenecks, are not necessarily a problem for today’s models. Improved automation and virtualization management tools have finally made good on the promise of simplified failover. In this tip, an expert explains why his feelings on blade servers have changed over the years, and why he now thinks they are the best choice for a virtual environment.

Blade server technology faces virtualization hit in the data center
Blade server adoption in the data center has slowed for a variety of reasons, including the rise of virtualization and a wealth of hardware and network factors. While deploying blade servers can offer an organization many advantages, they aren’t right for every environment. If an organization doesn’t use enough blades to fill a chassis, many of those potential cost saving advantages may not be realized. IT professionals that deploy blade servers without conducting a detailed cost-benefit analysis could end up disappointed–or over budget.

Cooling blade servers
Blade servers pack more computing power into a smaller area, but that also means that one of the biggest challenges with using blade servers in the data center is keeping them cool. Even in a data center with enough cooling capacity, data center professionals using blade servers can find themselves struggling to address hot spots caused by blades. This Q&A addresses the classic question of, “How much air movement do I need to properly cool a blade server?”

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