Virtual CPU definitions FAQ
The virtual CPU definition helps make sure that virtual machines can run on different types of physical hardware.
For information about updating the virtual CPU definitions for your VMs and templates, see Updating CPU definitions.
Questions
Q: What is a virtual CPU definition?
A: A virtual CPU definition, also called a CPU mask or CPU compatibility mask, allows customization of the CPU features that are visible to a VM. Skytap uses CPU definitions to help VMs run seamlessly on different physical hardware types.
Q: Does this affect everybody?
A: Yes and No. Every VM gets this update—in most cases, automatically. If you have a VM in a state that prevents the automatic update, Skytap Support will email you to let you know.
Q: Are some operating systems more likely to need the update than others?
A: Yes. Windows 7 and Windows Server 2008 R2 VMs often need to be rebooted or reactivated. The update reduces the frequency of reboots and reactivations.
Q: What happens after the update is applied?
A: Some operating systems may require new CPU drivers or reactivation of the OS. The good news is that after the update, you won’t have to install new CPU drivers or reactivate your OS just because you move your VM to other regions.
Q: What about my templates?
A: If environments that you create from templates frequently require new CPU drivers or OS reactivation (common for Windows 7 and Windows Server 2008 R2 VMs), you probably need to make new templates. For detailed instructions about updating CPU definitions in templates, see: Updating CPU definitions.
Q: What happens if I don’t shut my VM down?
A: You won’t receive the update, which may cause unexpected behavior. Particularly for Windows 7 and Windows Server 2008 R2 VMs, reboots and re-activations may become more frequent. The update reduces the frequency of reboots and reactivations.
Q: Do the public templates use the new virtual CPU definitions?
A: We’ve already updated the Skytap public templates to use the new virtual CPU definitions.
Q: How do I know if I need this update?
A: If your VMs frequently require you to reactivate the OS or install CPU drivers, or if software on your VM requires reactivation, you probably need the update. These events are more likely to occur for Windows 7 and Windows Server 2008 R2 VMs. The update reduces the frequency of those events.