When it comes to management and support for IT shops running multiple systems, VMware ESX Server beats Xen and Microsoft's Virtual Server hands down, say Scott M. Herold and Ron Oglesby, authors of VMware ESX Server: Advanced Technical Design Guide.
Discover tips for running ESX Server in Linux and Windows environments and learn how to avoid the "Windows sprawl" by keeping an eye on virtual machine growth. Find out why design issues encountered when using ESX Server are the same for Linux and Windows shops.
SearchOpenSource.com: What advice about gotchas and best practice tips would you give for someone running VMware ESX Server with Linux?
Ron Oglesby: I would warn Linux shops not to think of ESX as Linux. Often, they see the console operating system and try to load it up and configure it like one of their standard Linux servers.
Scott M. Herold: If you're using Linux and there is a dire need to use a 2.6 kernel in a VM [virtual machine], wait for ESX 3.0. VMware ESX Server has been plagued with time-keeping and performance issues that are reportedly resolved in the 3.0 version. I have personally configured and run 2.4 kernels inside of virtual machines that performed as expected for some large organizations only to see the same applications run degraded on a 2.6 kernel.
What different issues come up in Windows environments?
Oglesby: With Windows I would say people need to stop trying to make their VMs into physical servers. Over-allocating processor and memory because they can, and seeing a server that runs a report once a week with dual procs and 3 GB of memory drives me crazy for sure when they start saying 'Our ESX system is slow.'
Herold: In addition to what Oglesby says about over-allocating virtual machines, managers also need to watch their growth. With how easy it is to configure a virtual machine, I see many organizations falling into the trap of deploying in too many instances, which leads to 'Windows sprawl.' This is the same problem that plagued many organizations in the physical world. The only difference is now they are only paying for operating systems' licenses and maintenance, not hardware.
For enterprises running multiple operating systems, is one virtualization platform a better choice than others?
Herold: [In environments with] heterogeneous operating systems, VMware is the clear leader. Microsoft's recent addition of Linux support to Virtual Server shows they are moving in the right direction. While Xen has consistently mentioned that they have been able to get Windows booting, it has been eerily quiet lately on that front.
[When] referring to varying service levels of an organization's environment, then VMware and Xen both show a strong presence in the market as being fully capable of simultaneously running production and development workloads on a system. Microsoft is behind its competitors in this area.
Oglesby: At this stage of the game, VMware is, by far, the better solution for a mixed environment. Xen can give it some competition in the Linux space, and Microsoft can make its normal arguments for Virtual Server; but VMware is, hands down, the winner right now.
From support and management standpoints, VMware has it all over the others. The ability to run almost any x86 operating system in one environment using one set of management tools would be my key factor in choosing VMware over the others in mixed environments.
How can IT shops using ESX Server optimize their performance to get the most out of their virtual machine?
Oglesby: Don't over-allocate, specifically, on the processors. If a server/VM isn't going to use a dual processor or can use a single processor, then only give it a single processor. Giving VMs dual or quad virtual processors places unneeded load on the host. Design the VMs to fit the requirements of the application and don't get stuck in 'We have to give everything two processors and 4 GB of memory because it's our standard.' It's a brand new virtual world. Embrace it.
Herold: Plan well. Nearly every organization is looking at virtualization and testing various products. If you are unsure of how to best use the technology, get help. There's no lack of organizations that are offering VMware services. There are also plenty of free resources to help educate architects on making the proper decisions for their organization. You don't want to be one of the few architects who says, 'This virtualization thing does not work.' There are plenty of people who have already proven that theory very wrong.
What are common design issues that IT managers may come up with when using VMware ESX Server with Windows? And with Linux?
Oglesby: On the design side, I think Windows and Linux environments see the same issues. The issues they see come down to the current infrastructure and how people do things today. Most organizations are completely hung up on existing processes because they have a vested interest in maintaining the status quo.
Network design issues are always huge discussions when using ESX. Do you use port trunking or not? Should you support Test and Dev on the same servers as Prod VMs? What about supporting DMZ VMs on the same servers as Prod-internal VMs?
After networking, I would say the next longest discussions are around SAN design and storage tiering.
Herold: The main design issue I see with ESX architectures is the lack of flexibility surrounding the infrastructure services (SAN, network, security, monitoring, backup recovery). In large organizations, there are often power struggles between infrastructure teams in regards to who controls specific aspects of the infrastructure. Virtualization not only requires the operating system and hardware engineers to change their operations methodology, but also requires all of the auxiliary services to review their practices as well. When organizations finally see success in virtualization and the supporting services also see the benefits, they are eventually willing to give up a little control of their particular environments to the larger cause.
What does VMware have to offer IT managers in the realm of management tools?
Oglesby: VirtualCenter(VC) is VMware's cornerstone management tool for its virtual environments. The new versions of VirtualCenter are getting pretty close to being what IT management needs, albeit for VMware-only environments. VMware is also opening this up so that ISVs can build solutions that cater to the needs of customers that might run mixed environments or have needs that VMware doesn't fill. Vizioncore [Inc.] is a great example of this -- trying to build a better middleman/broker of performance information for any type of monitoring software.
Herold: The only tool VMware provides is VirtualCenter. After some pretty harsh feedback on the 1.X version, VMware is making some great strides with the 2.0 version scheduled for release with ESX 3.0. With the Community Source program, we should see a completely new level of integration from ISVs and how they interact with the VMware Virtual Infrastructure.
This was first published in June 2006