How to migrate from vSphere ESX to ESXi

Now that VMware has announced that vSphere ESX 4.1 will be the latest version that will be having a Service Console. They also annouced that customers who are running vSphere ESX should upgrade to vSphere ESXi in 8 to 12 months.

In this post I will discribe the (non-technical) procedure how to migrate. Non technical because I assume you guy’s will all probably know how to install ESXi, vCenter, create a cluster etc…

So how can we migrate to vSphere ESXi? Let us assume we have a vSphere ESX 4.0 with vCenter 4.0 enviroment who we want to migrate to vSphere ESXi. First step we have to take is to upgrade to vSphere ESXi 4.1 with vCenter 4.1. Where the upgrade to vCenter 4.1 is the first step.

As you all probably know, as off vCenter 4.1 you cannot install install this on a 32-bit operating system. So in case you’re running vCenter of a 32-bits Windows 2003 or Windows 2008 you’ll have to install a new (virtual) machine where you can install vCenter 4.1 on.  If you want to migrate the vCenter database to the new machine, check this KB article of VMware. If the information inside your database isn’t that much of a value you can install a clean copy of your vCenter.  Warming! When you are running Distributed Switches, it’s best to migrate temporarly to standard vSwitches and later on back to a Distributed Switch. This, because the configuration of a Distributed Switch is located on the vCenter host. The vSphere host only has the running part who cannot be modified without vCenter.
Make sure you keep you current vCenter server up and running so you can check the setting later for the new vCenter server.

Once you have installed  your brand new vCenter server, you can begin adding the existing vSphere host. For now we will add the vSphere hosts to the new vCenter server not being a member of a cluster. Why? High Availability (HA) makes use of a agent on the vSphere host. Later on, we will be reinstalling these host with ESXi. So adding them now to a cluster has no advantages.   If the time between adding the host to the new vCenter server and the reinstall of the hosts with ESXi is long, you can make the hosts member of a cluster, but I think that most upgrades won’t take that long.
When you add a host who is a member of another vCenter server, you will get a message like: “The host is already being managed by IP Address:……..”. This OK and you can proceed with the normal procedure.

Now that the hosts a member of the new vCenter server. It’s time to reinstall the hosts with vSphere ESXi. You can download your version of ESXi here.
When you reinstall the hosts with ESXi, make sure you know how the host is configured now before whipping the host completely. Think off:

• Host name
• IP Adresses (including default gateway, dns server, NTP etc)
• Network configuration
• Storage configuration

Finally after  reinstalling the vSphere ESXi host you can (re)create the new Cluster with all his features. If you didn’t delete you orginal vCenter server, you can check the setting from the original cluster for the recreation.

So there you have it. Now where ready (again:-)) for the future.