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Server selection and VMware: Physical boxes or virtual machines?

Learn about data center power and space problems, whether or not a company should jump straight into VI3, and how virtual servers change physical server requirements.

Choosing servers is no longer a process completely focused on processor speeds, IOPs (input/output operations per second), memory busses and network adapters. There is a new server in town, the virtual server, which complicates matters even as it eases some data center pains.

In this tip, we look at issues data center managers evaluating both virtual and physical servers should take into consideration before making their choices.

Data center power and space problems
Obvious pain points are driving the adoption of virtual servers. These include the need to bring more business applications online in even shorter time frames to stay competitive and the need to continue to support legacy systems that are required for regulatory compliance. But where are they going to put all these new application servers with all the legacy servers taking up floor space?

Data centers have run out of space, power and cooling, and the costs to build new data centers -- even if the local power grid could support it -- is extremely expensive and time consuming. This is particularly painful when most of the servers filling current floor space are only running at less than 10% utilization.

I was speaking with one operations manager recently who is flat out of power. She has recently been tasked with incorporating

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departmental legacy servers to make sure the data assets are secure and backed up into her data center. This has completely maxed out her power capabilities, keeping her from being able to deploy new applications.

Updates in technologies are also driving data center managers to evaluate server choices, especially their x86 choices. Technology advancements -- such as faster processors, the advent of quad-core architectures, larger memory sizes, faster I/O pipes with 10GbE and 8GbFC and the broader availability of server virtualization – are creating the perfect storm for consolidating under-utilized and legacy systems.

Two tough server virtualization questions
In this world of pain points and exciting new technologies, what should data center managers evaluating both virtual and physical servers take into consideration before making their choices? Here are two common conundrums:

  • Should a company invest in VMware's Virtual Infrastructure 3 (VI3) from the start or first familiarize yourself with virtualization by using VMware Server?
  • How does the use of server virtualization change the physical systems requirements? Can one use the systems one currently has?

There are two server virtualization solutions available from VMware.

    VMware Server (formerly GSX) was the first server virtualization solution available from VMware. It uses a hosted virtualization architecture which means the virtualization software sits on top of the base operating system, requiring the application data to traverse many layers to access devices. However, because the server virtualization layer resides in the user space of the operating system, just like an application, it is very easy to implement and perfect for test driving virtualization or for very small virtualization implementations. Also, it is free.

If you are ready to make a strategic commitment to server virtualization in your data center, I see several reasons why VWmare VI3 is what you should be deploying.

One compelling reason is that the ESX hypervisor architecture is significantly lighter- weight than the hosted architecture, enabling higher application performance in the virtual environments.

When it comes to data centers, performance is important but efficiency rules. That is where the rest of the VI3 comes into play. VMware has done an excellent job of creating a full-featured virtualization ecosystem in support of data center deployment. At the base level, that is, the components that interact with both the hardware and the virtual servers are the hypervisor options (ESX Server 3 and 3i) with basic capabilities in support of a shared file system (VMFS) and virtual symmetric multiprocessing (Virtual SMP).

To build on these basic capabilities, VI3 contains a second layer of components that provide support to the virtual ecosystem. These capabilities include the ability to incorporate VMware products and features, such as high availability with VMware HA; virtual resource management via VMware DRS; and backup via VMware Consolidated Backup. There's also virtual machine mobility, or the ability for virtual machines to move from one system to another, which are facilitated by VMware's VMotion and Storage VMotion and update management.

The third layer of capability in VI3 is the management layer allowing data center managers to optimize their existing infrastructure with VMware VirtualCenter, Converter and Capacity Planner and provide disaster recovery capabilities with SiteRecovery Manager. There's the option to manage the life cycle of the applications installed within the virtual infrastructure with VMware Lab Manager.

In my opinion, VI3 is the most comprehensive data center-ready virtualization ecosystem available today. If you have made the strategic commitment to virtualization and are ready to move forward today, VI3 is the right choice.

Hardware choices in virtualized environments
What about those processor speeds, IOPs, etc.? Can I use my current systems to deploy virtualization or, if not, what do I have to consider when purchasing new hardware?

When deploying virtual servers, it is imperative to take into consideration the ramifications these new virtual servers will have on the physical server. First and foremost, you will be moving to a shared environment. That can mean contention for processors, memory and I/O. It also means you are now putting more servers onto one physical system; if the system fails, it's not just one application that will be affected, but many. This requires that the physical system be fault-tolerant or configured for high availability.

Memory is another area to be pondered when configuring your virtual server system. Most applications behave badly when there isn't enough memory available. So, when deciding on the amount of memory required by the system, purchase extra headroom to accommodate peaks.

Input/output is another area that can become a bottleneck in a system running virtual servers. The good news is that there are a number of advanced-functionality NICs available that supply high bandwidth and offload network processing to free up the CPUs for server work. Many of these NICs also support virtual NICs in support of virtual servers.

Finally, to take full advantage of VMware's VI3, you will have to implement networked storage, if you haven't already, between all the virtualized servers. This allows all systems to see and access the data, a requirement if you want to be able to move virtual machines from one system to another for dynamic resource sharing or high availability. Either SANs (Storage Area Networks) -- iSCSI or Fibre Channel -- or NAS (Network-Attached Storage) can be used as the basis for a network storage infrastructure.

With all this in mind, what is the answer to the question, "Can I use my current servers?" It depends. It depends on whether the systems are fairly current and meet the above considerations and it depends on your application mix. If you intend to use current servers, it's more than likely that both memory and I/O will have to be upgraded.

Today, data center managers have even more "server" options to choose from, both physical and virtual, to address both their application requirements and their environmental requirements. That's good news, even if making the right choice is a bit harder.

About the Author: Anne Skamarock, Research Director at Focus Consulting (www.focusonsystems.com), has been involved with computers and associated technology for nearly 30 years. For the past seven years, Anne has worked as a market analyst focusing on the convergence points around systems, storage, and software. Anne has published extensively including regular columns and tips for TechTarget's SearchChannelStorage.com and Network World, and numerous business and technical white papers. She has recently finished her second book as co-author of Blades and Virtualization: Transforming Enterprise Computing While Cutting Costs.

This was first published in November 2007

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