Are VMware shops ready to move from vSphere ESX to ESXi?

VMware said vSphere 4.1 is the last version to offer both ESX and ESXi. Users may finally be willing to give up the Service Console in classic ESX

VMware has put a lot of effort into the vSphere 4.1 release, and with it, VMware made it official that vSphere 4.1 is the last release from the virtualization giant that will contain both the "classic" version of ESX that we've all become familiar with, and the newer, slimmed-down version, called ESXi. From now on, all new releases of vSphere will only include the ESXi hypervisor.

VMware's classic ESX hypervisor includes a user space environment, known as the Console Operating System (COS) or Service Console, which is derived from a distribution of Linux. It's used as both a bootstrap for the VMware kernel and as a management interface that could be automated and queried against using Linux-style commands and scripts.

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The COS is being deprecated as VMware moves to exclusively using the embedded or trimmed-down version of ESX, the ESXi model. This makes the hypervisor footprint substantially smaller and potentially more secure and efficient. The smaller hypervisor footprint also provides users with delivery mechanisms beyond installation on local storage such as SD cards, USB memory sticks, or even being embedded on the server hardware itself before ever leaving the factory.

But if ESXi is so great, why has VMware had its work cut out for it in convincing skeptical customers of the value from moving from ESX to ESXi? The company has been promoting it for years now, and it has even made the ESXi offering a free hypervisor. But that's been part of the problem as well. By making it free and by creating arbitrary limitations around it, the ESXi platform for many has become thought of as a low-end, low-grade version of the superior classic ESX hypervisor.

One of the most common fears among die-hard ESX community members about moving to ESXi has been the loss of the COS and the ability to script or interactively SSH into the machine in order to perform management and command-line functions.

In the early versions of ESXi, VMware offered a Tech Support Mode (TSM) to users so that they could still log in interactively and work with the ESXi host machine. However, this method was labeled by VMware as "unsupported." To make sure administrators knew that this feature was unsupported, each time the admin would log in to TSM, they would have to type the word "unsupported," reaffirming that fact and providing VMware with a CYA should anything go wrong. While not ideal, this did appease many administrators who moved to the ESXi platform in some form or fashion. But as an unsupported option, this "feature" didn't necessarily go over very well with other admins who couldn't convince themselves to use it in a production environment.

VMware has definitely heard the battle cry from its community of users around this missing piece of functionality, and with the vSphere 4.1 release, VMware is expanding the Tech Support Mode of ESXi. Perhaps as a major concession to its user group's demand, the "experimental" restriction has been lifted with vSphere 4.1. This feature, along with SSH support, now gives ESXi a very similar look and feel to the old classic ESX model. Because of that, ESXi naysayers may have lost one of their biggest complaints against the new slimmed-down version of the hypervisor.

Jon Owings, a VMware vExpert from, said he finally admitted to himself that the VMware Service Console was going away during a private prebriefing he had on vSphere 4.1. It was at that point that he made the decision to finally start weaning himself away from relying on the VMware COS and start living a life free from that old Red Hat-like environment.

Owings said even without the COS, he figured he would have access to the same items he needed through PowerCLI and the VMware vMA appliance that VMware was now offering as alternatives. The move would allow him and his VMware environment to stay well ahead of the curve.

"I spent a few hours trying to convert all of my old ESX scripts and install kickstarts to work with ESXi," said Owings. "But I realized a lot is going to need to change."

Because the COS is still present in the latest version of vSphere 4.1, Owings said it was way too easy to cheat. If he couldn't find what he needed with PowerCLI or if the vMA didn't react just the way he liked, he could simply flip the support-mode SSH to enable and then run the commands he needed -- the old way.

"I deploy a new vSphere environment at least every two weeks, sometimes more," said Owings. "ESXi and the missing Service Console have slowed my rollouts slightly, which for now has me slightly frustrated. I know over time it will become like second nature, but for now I am just getting my processes perfected with ESXi. I do miss the Service Console, but I am not yet to the point of shaking my fist at VMware or doing something completely nuts like switching to Hyper-V."

Another VMware vExpert, Jase McCarty, has had similar thoughts and experiences with using or migrating to ESXi.

McCarty's current environment has been operating on VMware ESX technology for more than six years now, going as far back as ESX version 1.5. When he first started managing that environment, one of his tasks was to standardize the build of all ESX hosts to the same release version, configuration, and patch level. At the time, ESX 2.5 was the most current release available, and ESXi had not yet been realized by VMware, so there really was no choice to be made here yet.

Fast-forward a few years, and McCarty's environment was ready for yet another upgrade. This time, the VMware standard chosen was VMware VI3 version 3.5 -- but there was an alternative ESXi version made available, although it was still not chosen.

So why was ESX chosen this time over ESXi? McCarty said the most likely answer was his familiarity with ESX and the use of its Service Console. At that time, his environment still had a few console scripts that he relied on, although he admitted that he probably could have purchased some additional software packages to overcome those limitations. But since upgrading his environment from VI3 to vSphere, many of those custom scripts have gone away, and more automation has come into play.

"In addition to upgrading to vSphere, other things have changed in my environment, including my storage solution," said McCarty. "Some of the scripted backup processes that once were, have been replaced by automated utilities that were included with my updated storage solution. And many of the Service Console-based scripts I once used have been replaced by PowerCLI and Perl scripts."

With remote scripting and tasks now handled by his storage solution, McCarty found that he relied on the Service Console less and less -- except when doing a bit of troubleshooting in the environment.

Looking ahead, he said that ESXi has the Technical Support Mode which should help when migrating from ESX to ESXi. With new growth coming up in his environment, this time he plans on migrating from ESX 4.0 to ESXi 4.1.

"Will I miss the Service Console?" asked McCarty. "Maybe a little bit, but I think that ESXi should be mature enough to do the job."

Some of the best advice that I've heard from both Owings and McCarty, as well as other VMware administrators and architects that I've been speaking to lately, has been this: Get started now, become familiar with deploying and using ESXi, and start your migration plans now. Rather than continue to fight the inevitable, you might want to start adopting the ESXi technology in your environment now -- if not in production, at least get started using it in your development and test environments.

Because one thing is certain, if you want to continue using VMware vSphere into the foreseeable future, you'd better get used to the idea of ESXi. While some administrators may be threatening that users will have pry the ESX Console out of their cold, dead hands, there really isn't going to be another option available to VMware users beyond migrating away from ESX classic.

This news really shouldn't be taking anyone off guard or by surprise. For a few years now, VMware has been telling the world that the COS is going away and that the company was moving toward the ESXi platform as the only choice available. When VMware releases vSphere 4.5 or 5.0 in the not-so-distant future, this next upgrade after vSphere 4.1 will definitely no longer have the COS, and it will be the trimmed-down version of ESXi now being called "VMware vSphere Hypervisor."

It's coming, ready or not. Although the migration and learning curve may not be easy and full of sunshine and roses for everyone, do yourself a favor and start now so that you can be ready for when the time does come and your options become extremely limited.

This story, "Are VMware shops ready to move from vSphere ESX to ESXi?," was originally published at Follow the latest developments in virtualization and cloud computing at

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