Mr. Wade Reynolds, Software Architect, Engineer and Guitar-Dude
Wade A. Reynolds

Using VMware to cement server consolidation

MiMi Yeh, Assistant Editor

This article was originally published by Tech Target and is available online at,289483,sid39_gci1182981,00.html.

Because both Windows and Linux support it, VMware is the best virtualization solution for heterogeneous environments, say the authors of Advanced Server Virtualization: VMware and Microsoft Platforms in the Virtual Data Center.

In this interview, David Marshall and Wade Reynolds offer their advice on what to do in heterogeneous environments, explain why they believe VMware trumps Microsoft Virtual Server and give their suggestions for useful management tools.

For customers in a heterogeneous environment, is one type of virtualization software (VMware, XenSource, MS Virtual Server, etc.) better than others? If so, why?

Wade Reynolds: Absolutely! VMware is usually the best choice for existing heterogeneous environments. The VMware product line (VMware Workstation and VMware Server) supports Linux and Windows-based hosts, as well as a diverse set of 32-bit guest operating systems.

Microsoft only recently added support to Virtual Server for a limited number of Linux distributions. It remains to be seen whether Microsoft Virtual Server will be as good at running Linux guests as it is at running Windows guest operating systems. Xen suffers from the reverse problem, since it is good at running Linux distributions but not Windows.

VMware is much more established than competing virtualization technologies, and relative to Microsoft Virtual Server and Xen, it has a proven track record for stability in heterogeneous server environments. In time, this view will shift away from VMware, because they have direct competition vying for rich heterogeneous guest operating system support in virtual machines.

What does VMware have to offer IT managers as far as management tools?

David Marshall: VMware has come a long way quickly since it realized its server class virtualization products were missing a component. A desktop virtualization solution, VMware Workstation was sufficiently managed by its own single interface. But VMware GSX Server and VMware ESX Server were increasingly difficult to manage as more host servers entered the virtual farm. Although the host server's management interface could manage multiple virtual machines housed on a single physical server, it quickly became a daunting prospect for IT administrators to manage an entire virtualized server farm across multiple physical host servers.

Enter VMware VirtualCenter. This software package helps IT administrators to streamline management, monitoring and provisioning of virtual machines across the virtual infrastructure.

To further assist with managing a virtual environment, VMware released VMware P2V Assistant, which helps migrate or transfer an image of a physical server into a VMware virtual machine. Over time, the product has been refined from a 'works sometimes' and 'difficult to use' tool to a tool that is relatively easy to use.

You cannot talk about management tools without discussing VMware VMotion. IT managers are constantly looking for solutions to help provide high availability and keep Service Level Agreements (SLAs). VMware VMotion technology allows an IT manager to perform zero-downtime maintenance and to effectively balance workloads across the data center.

What would you say are some gotchas and best practices tips for running VMware ESX Server with Linux or Windows?

Reynolds: Like any other virtualization platform, planning is the key to success. Understanding exactly what your goals are relative to your constraints is very important. Know the specifications of the physical host server running VMware ESX Server and use case of the guest operating systems you plan on running in the VMs.

Having a good feel for the amount of CPU consumption, amount of memory needed, disk I/O intensity and detailed networking requirements and configuration will allow you to circumvent mistakes like purchasing underpowered or insufficient amounts of hardware.

It is important to learn the details of the virtualization platform. VMware provides very good documentation, especially regarding hardware and guest operating system compatibility. Before implementing VMware ESX Server in a production environment, it is best to get some 'hands on' time in a test lab scenario first. You should also research books and online resources, including blogs and forums, to learn about the successes of others with similar configurations/cases.

Since VMware ESX Server only supports SNMPv1, how do you guarantee confidentiality from a well-placed protocol sniffer?

Reynolds and Marshall: It is our belief that, as a best practice in enterprise environments like those running VMware ESX Server, strict network security should be enforced at the network infrastructure level. Access should be restricted to end-points, and protocols should be put in place for using firewall ACLs and VLAN architectures to isolate sensitive network segments, such as virtualization host servers. Enforcing sound security best practices in the organization, overall, should prevent access to someone that may want to use an unauthorized network sniffer. Other more sophisticated methods like intrusion detection systems may also be used.

What do you make of VMware's distancing itself from ESX?

Marshall: We don't believe that VMware is distancing itself from its ESX Server line. By giving away VMware Player and VMware Server, and opening up its virtual machine disk format specification, VMware is building a roadmap for IT consumers that leads all the way back to its ESX Server line.

If you are a newcomer to the virtualization space, you might be enticed to experiment with the free VMware Player. After becoming familiar with the product and its benefits, you or your company could end up trying your hands at VMware Server, only to realize that you need more power -- better resource management, more stability, larger scalability or additional add-on management tools. And because the virtual machines and virtual disks all have a migration path from one platform to another, all roads ultimately lead you to VMware's upper echelon of virtualization, VMware ESX Server.

Wade A. Reynolds is an architect at Surgient, Inc., a leading provider of on-demand applications based in Austin, Tex. Reynolds specializes in server virtualization, enterprise software development and database systems.

David Marshall is a senior member of the reference architect team at Surgient, Inc., and specializes in server virtualization, virtualization applications and Windows administration. He also runs the InfoWorld Virtualization Report as well as the virtualization news blog.

Together, they have written Advanced Server Virtualization: VMware and Microsoft Platforms in the Virtual Data Center, detailing their years of experience using and implementing server virtualization solutions