Caution: Articles written for technical not grammatical accuracy, If poor grammar offends you proceed with caution ;-)
Back in April I wrote a blog aimed and the differences between ESX and ESXi. The original post was written for ESX 3.5 and with the introduction of vSphere I think it’s about time i have revisited this topic and looked at the pros and cons of ESX4 and ESX4i. Now before we dig into the technical details there is one big thing you should all be aware of. The FAQ page published by VMware states “VMware ESXi is the recommended platform for both new and existing customers. Future hypervisor releases will solely be based on this architecture.”
For most that should be enough said. After reading that I would seriously start rolling out ESXi in a lab and start figuring out how I could maintain my needs without the service console most of us have become to know and love. I would also start brushing up on the RCLI as well as the PowerCLI if you are currently dependent on scripts that run in the service console. The good news is almost everything you do today in the service console can be achieved one way or another with ESXi as well. OK with that said lets talk about some of the other limitations.
I’m a very big fan of scripted installations. I think they promote efficiency, standardization, and stability. Granted if you are licensed for Enterprise you can utilize host profiles for post installation configuration but you still need to lay down your base ESX installation. Unfortunately today their is now viable way to script the installation of ESXi. You can order your servers with it already embedded which can help alleviate the pains of not having scripted installation capabilities but that’s about it. Post installation scripts are possible for both flavors. With standard ESX you can include your post installation as part of your kickstart to be deployed after first boot or you can leverage the vCLI to deploy post installation configuration for either flavor. As stated earlier if licensed you also have the option of utilizing Host Profiles.
Another point worth mentioning if you are intending on utilizing the free version of ESXi don’t plan on utilizing the vCLI or PowerCLI for configuration. VMware locked out the API utilized by these to only wok for specific license levels. They obviously so this to prevent 3rd party vendors from creating management tools for ESXi that would give the free users advanced functionality.
Boot From SAN
Another popular way to deploy ESX might be to utilize boot from SAN. Utilizing this model it’s possible to utilize SAN functionality to provision new ESX hosts pretty effortlessly. ESX supports boot form SAN however it does require a dedicated LUN per server but doesn’t require a dedicated HBA anymore. However it is still best practice to utilize dedicated HBA’s for your boot LUN. ESXi doesn’t technically support boot form SAN however it is achievable. Even though it is possible remember you would now be running an unsupported configuration which would make possible issues difficult to resolve with VMware support. Unlike ESX, ESXi does support booting form embedded flash media making it easy to duplicate flash cards to insert into servers that support the media.
Host Active Directory Integration
ESX supports active directory integration through the use of third party tools or through the configuration of kerberos within the service console. ESXi does not have any support for active directory integration today.
ESXi does not support web access. So if you have deployed a solution is dependent on the use of web access to directly access your ESX hosts this feature is not available in ESXi. I know what your thinking who could possible have a need to access the ESX/ESXi hosts through web access directly to the hosts. Well I will tell you who. Take a college for example. Colleges could provide students that are learning about computer and networking technologies with VM’s that site on a free ESXi server for learning purposes. They can’t give these users access to this for free today utilizing ESXi because the web interface doesn’t exist. So those that do this generally utilize the Free VMware Server distribution to solve this problem.
Troubleshooting and Support
What about the tools you are so used to utilizing today to troubleshoot issues with your ESX hosts. Well ESXi does have support for these tools. Most of these tools are available through the vCLI. When these tools are not enough you can utilize the DCUI which is the console interface that is available on ESXi to perform functions such as restarting services etc. There is also a Tech Support mode for the more advanced diagnostic troubleshooting. So if you are still hanging on to the past where ESXi was lacking some of the tools you had to have, don’t they are for the most part available today with ESXi in some form or another.
There are some additional considerations to think about. What about Updates? ESXi updates more like traditional firmware where ESX updates similar to standard Linux patches. The ESXi model can be more manageable and robust that that of ESX however with Update Manager the update process realistically isn’t much different and shouldn’t be a deal breaker for either version.
For those of you that actually install your hardware vendors agents in the console there are some benefits to ESXi. No more need to install agents. ESXi utilizing standards based CIM providers eliminating the need to actually install the usually problematic hardware vendor agents.
Ok with all that taken in to consideration ESXi get’s my vote. ESXi offers as much support as ESX today with a few missing features such as web access however most environments don’t have a need for this feature so I don’t see it as a show stopper. The ability to order a server from your vendor with ESXi installed is a huge benefit. Open box, rack, cable, boot, assign networking and other info, add to vCenter, appy Host Profile and your server is now ready to go very quickly and easily.