For a recent client, we needed to migrate VMs from one host to another. The goal was to use vSphere’s vMotion capabilities to move VMs from Host 1 to Host 2. Upon moving all hosts to the same vCenter Server, there was an incompatibility issue with the two hosts. Host 2 was using a Haswell generation Intel processor, the other, Host 1, an older Sandy Bridge. When vMotion is attempted, you get this error:
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The virtual machine requires hardware features that are unsupported or disabled on the target host
General incompatibilities
If possible, use a cluster with Enhanced vMotion Compatibility (EVC) enabed, see KB article 1003212.
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In order to perform the migration, vCenter needed an EVC cluster to be formed. This seems easy enough… simply forming a new cluster with EVC enabled for our lower Sandy Bridge processor and dropping in our hosts. It, however, was not so simple, because Host 2 was hosting the vCenter VM.
To sum it up, we wanted to create an EVC cluster and place Host 2 (that is hosting vCenter Appliance) into the cluster, in order to then migrate VMs from Host 1 (possessing an older Sandy Bridge processor) onto Host 2 using vMotion.
When trying to move Host 2 directly into the cluster, with the vCenter VM powered on, you will get an error because in order to move a host into an EVC cluster all of that hosts virtual machines must be powered off. This is where the issue arrives.
If you have hosts you can vMotion your vCenter VM to, then this is simple. Simply move it off of the host you wish to move, move the host to the EVC enabled cluster, then migrate vCenter back. But in my case, I didn’t have that sort of luxury. In order to move my host I needed to power off vCenter first, then migrate it. But, in order to migrate it, I needed to log in to vCenter, which I can’t do when it is powered off. The proverbial chicken and egg argument.
There are loads and loads of articles out there (notably KB article 1003212) that give you a complicated work around. But I have figured out something much more simple.
To recap, I want to do a hot migration (using vMotion) of VMs from Host 1 to Host 2. In order to do so, I need to my Host 2 to be in an EVC cluster to ensure CPU compatibility. To move Host 2 into an EVC cluster, I need this work around because Host 2 is hosting my vCenter:
0) Create a new cluster with EVC enabled for the limiting processor (in my case Sandy Bridge)
1) Clone your vCenter to another host (in my case, Host 1)
2) Name it vcentername-clone (vcentername is whatever your vcenter is named)
3) Power off your current vCenter
4) Login to Host 1 (where you moved vCenter to) through the vSphere Client
5) Power on the clone
* Note: In my case, my vCenter has a static IP. If you are using DHCP you may run into issues at this stage.
6) Once its done powering up, you can log into your vCenter again through the vSphere Client
7) Move Host 2 to the EVC cluster
8) Delete the original vCenter VM
9) Clone the vcentername-clone VM to Host 2 (the one that is in the EVC cluster) and name it vcentername (your original vCenter name)
10) Power off the vCenter clone
11) Power on the most recent clone in the EVC cluster by logging into Host 2 through the vSphere Client
12) Delete the vcentername-clone on Host 1
You now have Host 2 in an EVC cluster, hosting vCenter. This now enabled me to vMotion VMs from Host 1 (possessing a limiting processor) to Host 2.