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Factors to consider when using blade servers for virtualization

Using blade servers for server virtualization can be a great way to cut your customers' data center space requirements as well as their power and cooling costs. But virtualizing on blade servers introduces issues that don't exist on standard rack-mount servers. Find out what factors you need to consider and how to guide customers toward the right choice.

Solution provider takeaway: Learn which factors to consider when determining whether -- and which -- blade servers are a good fit for your customers' virtualization plans. 

The ever-increasing costs of data center space, power and cooling along with tightening IT budgets and scaled-back staffing have led your customers to look for new options while still providing the computing resources they need to successfully compete in the marketplace.

The newest solution to these challenges is the combination of virtualization and blade servers. Together, they can drastically reduce the amount of space required for a company's computing workloads. But before recommending virtualized blade servers, you'll of course need to examine whether or not they can address your customer's problems in a cost-effective manner. In other words, you need to understand what the core issues are in using blade servers for virtualization, as well as what can be accomplished via virtualization management tools.

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Before virtualization became such a prominent part of the IT landscape, blade servers were typically used for server clustering in a variety of tasks, such as file sharing, video, audio streaming and Web page serving and caching. Virtualization, however, places much heavier loads on a server than clustering does; multiple virtual machines (VMs) must share the CPU cycles, memory and I/O resources on the single physical blade server. This heavier load can cause performance bottlenecks.

To avoid the bottlenecks, you'll need to allocate 4 GB per virtual machine, which in turn will limit the number of VMs that can be hosted on a single blade server. Blades' limited network connections will also have an impact on the number of VMs possible on a single physical machine.

Beyond those factors, you'll need to consider the applications that will be hosted in the virtual sessions. Some applications may not work as efficiently in a virtualized environment as they do in a standalone server environment. One example of this is large-scale transaction processing applications, which generally haven't performed well in a virtualized environment.

Another example is applications that have very high read/write ratios; they could encounter performance issues due to factors such as bus speed, memory limitations, disk access and network I/O. Network I/O virtualization NICs from companies like Neterion and SolarFlare, combined with hypervisors that support multiple virtual network I/O queues, can help mitigate the issues that hamper the virtualization of these high I/O workloads. Unfortunately, some blades can't accept these NICs because they have a limited number of or proprietary expansion slots.

Blade server choices for virtualization

Once you've determined the viability of virtualizing your customer's current application environment and any special considerations, you need to determine the suitability of blade server offerings from various vendors to find the most cost-effective fit. In particular, you should look for blade servers designed or enhanced to handle the additional loads and challenges imposed by virtualization. You should also look for blade servers that provide the necessary software and tools to configure and manage the blades in-band or out-of-band, providing comprehensive information on the blade configuration, contents, component health and so on.

Major server hardware vendors such as Dell, HP, IBM and Sun are now marketing blade server models as suitable for hosting virtual environments. These manufacturers have increased the number of high-performance dual- and quad-core processors these systems can support, and they've significantly increased the amount of high-speed RAM available in the blades. They have also expanded network connectivity and I/O capabilities to provide more high-speed connections, such as 10 Gigabit Ethernet, for virtual sessions. In most cases these systems now support from two to eight network connections.

HP, for its part, recently announced a new model of blade server that it designed from the ground up for virtualization, with as much as 128 GB of RAM. While the new model compares favorably with other systems in the dual-processor class, other manufacturers have some very good quad-core processor configurations that definitely warrant a closer look. Some of these can hold up to 192 GB of RAM along with eight processors and eight NICs.

These manufacturers are also leveraging key processor technology enhancements such as the AMD Rapid Virtualization Indexing. These enhancements allow virtual machines to directly manage memory and reduce hypervisor cycles, improving performance. These systems also support Fibre Channel SAN and virtualized storage solutions.

Blade server management features

Equally important to these new hardware enhancements are the software tools to rapidly configure and deploy these virtualized environments and manage and control the hardware that hosts them.

The most common tools and management features provided by the major blade server vendors are:

  • Optional embedded hypervisors from leading vendors such as VMware, Citrix, XenServer and Microsoft.
  • Utilities providing out-of-band remote management of multiple servers from a single remote GUI console.
  • Monitoring agents that provide out-of-band alerting, system status, system health, configuration information, system inventory and troubleshooting.
  • Utilities for vulnerability scanning, patch management and power management.
  • Virtual KVM support, providing out-of-band remote management.
  • Virtual media support, allowing you to map media from a remote workstation to a blade.
  • Utilities providing remote control of the server hardware.
  • Support for integration with third-party management solutions.
  • Specialized tools for rapid configuration and deployment of virtualized environments.

The embedded hypervisor offerings, primarily found on the Dell and HP systems, make it easier and faster to deploy a virtualized environment. The software management features vary to some degree by vendor. However, all of them provide basic functional remote control and monitoring of the systems as well as tools to make it easier to deploy virtualized environments and the blade servers themselves. Dell and HP in particular appear to be working hard to provide very robust management software for their blade servers.

By taking all these factors into consideration and carefully examining the models, expansion and storage options, and support options from various vendors, you can select the products and configurations that will best address a customer's needs in the most cost-effective manner. It doesn't matter if customers are just beginning the creation of their virtual plan or well down the road to virtualization and are looking for more efficient options in the use of power, cooling or space. If offering virtualization strategies is key to your business, it pays to know when and how to leverage blade solutions in your plans.

About the author
Joseph Ortiz is a senior analyst at Storage Switzerland LLC. Prior to joining Storage Switzerland, Joseph ran his own consulting firm, providing professional services for data protection processes. His 28-year background in the industry includes a stint as lead technical engineer for several VARs and IT system integrators as well as engineering roles at two data protection software manufacturers.


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