Switching host to EVC and VMs

[Bernd_Nowak]

When I have a cluster and host(s) with EVC and start VMs which had been working without before I assume that Windows will 'notice' a hardware change and force a reboot? Is that all I need to fear?

Like I wrote in the other thread it's from 54xx to 56xx where the old hosts with the 54xx will still be used. I need this to be prepared for downtime calculation and what can happen during the migration

[Troy_Clavell]

you can't add a host with running VM's into an EVC cluster.  When the guests power up, the CPUID bit will change, but the guest OS will not require an additional reboot.

If you have running VM's, you can follow the procedure below, even if you don't have vCenter running as a VM

Enabling EVC on a cluster when vCenter is running in a virtual machine

[Bernd_Nowak]

Thanks Troy just asking because I remember a ESX/vSphere upgrade from 3.5 to 4 where after upgrade of vmware tools and the needed reboot the windows hosts have discivered new hardware and needed a reboot to finish installation.

[Troy_Clavell]

yes, but EVC does not happen inside the guest, so there is no reboot required. Upgrading the VMware tools, and vHardware of guest would indeed require a reboot.

[Bernd_Nowak]

So a valid way would be to add one host to a new EVC enabled cluster. Then power down one VM after another on the old cluster on one host and migrate it to the new EVC enabled cluster host. When one old host has no more VMs on it remove it from the old cluster and reassign it to the new cluster?

This would be something we can schedule with the regular windows updates

Need to check the vCenter stuff however but this should be not a real problem.

[Troy_Clavell · Accepted solution]

yes, if you have a downtime window, a cold migrate would work.  When the guest is powered on, the CPUID Mask will be changed to reflect the EVC mode you are running in.

There are ways of doing it hot, but it's not 100%, so you may want to look at the KB article posted above.

However, if you can afford a total downtime of all VM's, just shut them down, disconnect the ESX(i) Host from the old cluster and then drag and drop into the new EVC Cluster and connect.  From there you can power on your guests.