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Test ESXi 4.1 today, migrate smoothly from ESX tomorrow

Virtualization Viewpoints is a semi-monthly column that discusses current VMware- and virtualization-related trends, news and topics. Here we offer opinions and viewpoints on the competitive, quickly growing and ever-changing virtualization industry with a focus on VMware, the current virtualization market leader, which is in an ongoing battle to remain on top and distance itself from its competitors.


VMware has long claimed that ESXi will one day be the Palo Alto-based company's main hypervisor, and the time has come for ESX to begin to gracefully make its exit. The recent release of VMware vSphere 4.1 will be the last release to include the ESX version of VMware's hypervisor, which may not make ESX fanboys happy. The improvements in ESX 4.1, however, demonstrate that the time to start switching is now.

In a recent Virtualization Viewpoints column, I wrote about drawbacks of VMware ESXi and why widespread adoption of ESXi is not a reality. Some of the problems with ESXi included:

  • No official support for booting ESXi from a storage area network (SAN),
  • no Web-based console to manage virtual machines (VMs),
  • no support for scriptable installations, and
  • no support for Active Directory (AD) integration.

The article also outlined several suggestions for making ESXi more attractive to administrators used to working with ESX. While I have always preferred ESX over ESXi, I am now recommending that you start using ESXi and plan on migrating all of your current ESX installations to the ESXi platform.

vSphere 4.1 is officially ESX's last hoorah

Why the change of heart? Several reasons. The first is that the newly released vSphere version 4.1 is the last major vSphere version that will include ESX and its service console. VMware stated in a blogger-only early access webinar that ESX will not be included in future releases and updates.

Until now, VMware representatives had stated that at some point in the future ESX would no longer be included in vSphere, but gave no indication as to when that would be.

VMware's biggest challenges in moving from ESX to ESXi were getting third-party vendors to migrate their applications which leverage the ESX service console to instead use VMware advanced programming interfaces (APIs), and getting ESXi features and manageability on par with ESX features and manageability.

Since VMware has now stated that ESX will not be supported in the next release of vSphere, you're going have to accept that you'll be migrating to ESXi in the near future whether you like it or not. Fortunately VMware engineers have made many improvements to ESXi in vSphere 4.1. This ESX/ESXi comparison matrix shows that the features that were supported by ESX 4.0 and not ESXi 4.0 are now present in ESXi 4.1.

ESXi 4.1 improvements

Technologies such as AD integration, boot from SAN and scriptable installs are now supported by ESXi. VMware has also improved the manageability of ESXi by making many changes to the Tech Support Mode and Direct Console User Interface (DCUI). ESXi now also officially supports Tech Support Mode. You can now configure and lockdown Tech Support Mode using the vSphere Client as well as access it remotely using a secure shell (SSH) client. Improvements were also made to the vSphere command line interface (CLI), such as the ability to forcibly terminate a VM that is not responding to normal commands.

There are still a few things missing from the DCUI that I would like to see added, like the ability to start and stop VMs. Hopefully VMware will add this functionality in the next release.

To avoid confusion about the forced switch from ESX to ESXi once ESX is no longer available, VMware has rebranded ESXi free edition "vSphere Hypervisor," and refers to both ESX and ESXi as "hypervisor architectures," effective immediately. The idea is that a generic name should make the transistion easier. Personally I think it has the potential to confuse many people -- hypervisor architectures is a bit vague and not a definitive name for a product.

Advantages of ESXi over ESX

ESXi has always had one advantage over ESX; the patching mechanism for ESXi is much simpler and easier than ESX's, which can be quite complicated. Every ESXi update/patch is a single ISO file (archive file) that replaces the previous one, which is saved as a fallback option. With this method you do not have to worry about patch dependencies and applying patches in a certain order, making patch installation and delivery much easier.

ESXi has some additional advantages over ESX, such as being able to boot from a USB flash drive, which can help reduce expenses, makes for easier installation and provides stateless computing. In addition, ESXi's smaller footprint makes it easy to install and gives it a quick boot time.

Why switching to ESXi today is a smart idea

VMware has put a lot of focus and development effort into the vSphere 4.1 version of ESXi and it shows. While VMware may have had a difficult time convincing customers to switch to ESXi in the past, the company has now provided some compelling reasons that should make migrating to ESXi a much easier decision.

Dropping ESX will allow VMware to focus on a single architecture, as it will no longer have to support two hypervisor architectures. "Cutting the fat" should make things much simpler in terms of development, compatibility and support. This could be a big win for the customers as they will no longer have to choose (or be confused about) two separate architectures. Designing, implementing and maintaining a vSphere environment will also become easier and less complicated.

How to switch from ESX to ESXi

To aid customers in making the jump from ESX to ESXi, VMware has launched the ESX and ESXi Info Center, which provides a lot of information about ESXi, including an ESXi 4.1 migration guide.

If you are predominantly an ESX shop today you should start migrating to ESXi very soon. It is best to gain experience with ESXi over time instead of trying to quickly adapt once the next major version of VMware's hypervisor is released and ESXi is the only option.

To migrate from ESX to ESXi, VMware recommends that you roll out ESXi in a test environment to familiarize yourself with the key management and architectural differences. Following that, you should familiarize yourself with the vSphere CLI and the PowerCLI remote command-line management utilities.

You should then ensure that your current third-party backup and system management utilities will work properly with ESXi. Finally you should develop an upgrade plan and begin upgrading your ESX hosts to ESXi.

We'll miss you, Elastic Sky X, and will treasure the many fond memories we have had as we move forward into the future that is ESXi.

ABOUT THE AUTHOR: Eric Siebert is a 25-year IT veteran with experience in programming, networking, telecom and systems administration. He is a guru-status moderator on the VMware community VMTN forum and maintains VMware-land.com, a vSphere information site.


This was first published in July 2010

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