6.5.1

Table Of Contents
Procedure
u
Enable the AMD Opteron Gen. 3 (no 3DNow!) EVC mode for your EVC cluster.
The steps to enable the EVC mode dier depending on whether you are creating a cluster or enabling
the mode on an existing cluster, and on whether the existing cluster contains powered-on virtual
machines.
Option Description
Creating a cluster
In the New Cluster wizard, enable EVC for AMD hosts and select the
AMD Opteron Gen. 3 (no 3DNow!) EVC mode.
Editing a cluster without powered-
on virtual machines
In the Cluster Seings dialog box, edit the VMware EVC seings and
select the AMD Opteron Gen. 3 (no 3DNow!) EVC mode.
Editing a cluster with powered-on
virtual machines
The AMD Opteron Gen. 3 (no 3DNow!) EVC mode cannot be enabled
while there are powered-on virtual machines in the cluster.
a Power-o any running virtual machines in the cluster, or migrate them
out of the cluster using vMotion.
Migrating the virtual machines out of the cluster with vMotion allows
you to delay powering o the virtual machines until a more
convenient time.
b In the Cluster Seings dialog box, edit the VMware EVC seings and
select the AMD Opteron Gen. 3 (no 3DNow!) EVC mode.
c If you migrated virtual machines out of the cluster, power them o
and cold migrate them back into the cluster.
d Power on the virtual machines.
You can now add hosts with AMD processors without 3DNow! instructions to the cluster and preserve
vMotion compatibility between the new hosts and the existing hosts in the cluster.
CPU Compatibility Masks
CPU compatibility masks allow customization of the CPU features visible to a virtual machine.
vCenter Server compares the CPU features available to a virtual machine with the CPU features of the
destination host to determine whether or not to allow migrations with vMotion.
To guarantee the stability of virtual machines after a migration with vMotion, VMware sets the default
values for CPU compatibility masks.
When a choice between CPU compatibility or guest operating system features (such as NX/XD) exists,
VMware provides check-box options to congure individual virtual machines. You can access the
conguration options through the Advanced Seings option for the CPU of the virtual machine. For more
control over the visibility of CPU features, you can edit the CPU compatibility mask of the virtual machine
at the bit level.
C Changing the CPU compatibility masks can result in an unsupported conguration. Do not
manually change the CPU compatibility masks unless instructed to do so by VMware Support or a VMware
Knowledge base article.
CPU compatibility masks cannot prevent virtual machines from accessing masked CPU features in all
circumstances. In some circumstances, applications can detect and use masked features even though they
are hidden from the guest operating system. In addition, on any host, applications that use unsupported
methods of detecting CPU features rather than using the CPUID instruction can access masked features.
Virtual machines running applications that use unsupported CPU detection methods might experience
stability problems after migration.
Chapter 11 Migrating Virtual Machines
VMware, Inc. 131