Administrators don’t like to bring down running workloads if it can be helped, particularly in 24/7 environments. As such, the ability to hot add resources – that is, add additional resources to a running virtual machine – such as RAM and CPUs is important to many.
For those that are running the latest and greatest – vSphere 5.1 and Windows Server 2012 – this feature may be a bit problematic due to a known issue, but the issue only manifests itself in specific circumstances:
- You must be running vSphere 5.1 on the host
- The virtual machine must be running Windows Server 2012 Data Center
- The virtual machine is configured to use hardware version 9
In these instances, administrators are able to actually add the resources to the virtual machine, but those resources don’t actually become available. Until a fix is implemented, VMware recommends using virtual machine hardware version 8, which is not affected by the issue.
For more information, visit the support page on this issue.