Server form factors: A guide to rackmount, blade servers and more
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Nothing inspires debate among IT managers like the question of which server hardware platform to choose for their virtualization deployment. On one hand, some organizations opt for generic rack servers, which typically feature a lower entry cost, and do not require any modifications to a data center's power supplies.
Other IT managers feel that the benefit of the centralized management console offered by blade servers is great, and that the integrated blade enclosure provides important power, cabling and infrastructure efficiencies that IT managers grappling with cramped data center quarters cannot afford to pass up.
In this face-off, two seasoned IT professionals and virtualization architects debate rack vs. blade servers, explaining the benefits of each architectural choice in a virtual environment.
Rick Vanover: Server racks the way to go
Chris House: Blade servers always win
Server racks the way to go for mainstream virtualization
By Rick Vanover, Contributor
The choice between rack-mount versus blade server platforms is a very complicated and important part of architecting virtualized infrastructure. But when it comes to selecting between these two server platform models, I believe that rack-mounted servers are the way to go for effectively all-virtual implementations. Here's why:
Rack-mount servers will always have a lower cost entry point than a blade-based installation. This aligns with standard virtual rack implementation practice of starting out small to prove a new technology then ramping upward in scope. Deploying a blade system to prove a concept for traditional server virtualization or a pilot virtual desktop infrastructure (VDI) solution can be a pricey experiment.
Putting price aside, one argument for blade servers is enhanced blade management from the chassis management suite. This functionality, while nice, can be made less of an advantage by automating many of the same functions at the virtualization platform level with cloud services such as VMware vSphere's new host profiles. vSphere host profiles allow host configuration via policy at the vCenter server level. This ensures that host servers are configured correctly in areas such as networking, storage and security.
Similarly, in Microsoft Hyper-V environments, host provisioning can be used to manage and deploy configurations centrally through System Center, PowerShell scripting, Windows Deployment Services, Group Policy and Active Directory.
Both of these examples can be used to manage rack-mount servers for virtualization as easily as blades, and in most cases with little or no added cost.
Another key consideration is supportability. How well will your staff be able to support this new platform? Chances are rack-mount systems will be easier to maintain than blade equivalents. This is particularly relevant in assessing factors such as power management.
If you were to install the new Dell PowerEdge R210 with its lower energy requirements, for example, it would likely fit into your data center with no power supply modifications. When it comes to blades, however, most models require additional power at higher amperage that could be difficult to sustain in today's cramped data centers.
Ultimately, it comes down to price and what you want to do with the platform. For most environments, the comfort level of rack-mount servers leads to an easy migration to a virtualized data center.
Rick Vanover (VCP, MCITP, MCSA) is an IT Infrastructure Manager for a large financial services organization in Columbus, Ohio. Rick has years of IT experience and focuses on virtualization, Windows-based server administration and system hardware.
When comparing blade servers to rack-mounts for server virtualization, blades always win. It makes sense to implement them together because both technologies reduce infrastructure by reclaiming data center and desktop space, improving management, while increasing data and application visibility and high-availability.
The centralized management console in blade enclosures such as HP BladeSystem's Onboard Administrator, for example, allows administrators to quickly see an overview of the physical server environment including names, IP addresses, hardware configurations, firmware revisions and operating status.
With all the necessary information centrally located, administrators are able to physically control server power, view the server console, respond to alerts and delegate resources such as Ethernet and Fibre Channel through technologies such as HP VirtualConnect.
Compared to rack-mount servers spread throughout the data center, blades ease server management by reducing the number of places an administrator must physically visit.
The blade infrastructure itself is also more efficient than rack-mounts. Consolidated power and cooling inside a blade enclosure reduces the number of power supplies and fans required. Rack-mounts, on the other hand, each need several fans and power supplies for just one server.
Integrated Ethernet and Fibre Channel switches within the blade enclosure likewise help to increase efficiency by reducing cabling requirements and combining them behind the switches on the blade enclosure backplane. With rack-mounts, you need dual power feed cables, two or more Ethernet management and network connectivity cables (including separate Ethernet for IP-based storage), two or more Fibre Channel cables to access a storage area network and keyboard/video/mouse adapters to view the server console if the rack-mount server does not have any form of integrated management. All this cabling can block airflow and become a management nightmare if not carefully labeled and organized.
Blade servers have become pretty common in data centers across the world, but another form of blade technology to consider exists in the form of blade PCs. These blades are smaller than their server counterparts but embody the same benefits as blade servers.
The bottom line in any blade server or blade PC comparison to a rack-mount installation is the combination of virtualization and blade technology. That's hard to beat in terms of decreasing infrastructure and increasing the efficiency of time-starved data center administrators.
Chris House is a VMware Certified Professional with five years experience managing the implementation and ongoing maintenance of VMware Virtual Infrastructure for desktops and servers and its associated components. He also manages storage and data center operations and maintains HP-UX, Linux and Windows server systems.