Andy Fox | 20 July 2012

In this blog we look at how to disable in check performed to test if a virtual machine has a connection to an “Internal Network” during a vMotion migration.

In many of the VMware courses it is stated that if a virtual machine is connected to a "Internal Only" virtual switch is cannot be migrated to another host with vMotion migration. This is because a check is performed on the virtual machine network configuration to ensure that it will be accessible after the move, and when connected internally that would not be the case, and from a production perspective makes perfect sense. There would be no point in migrating a virtual machine from one host to another if it could not then communicate with other virtual machines also connected to the same internal network.

From a test and development perspective, this may be desirable. For example, you may be testing a multitier application (using more than one vm), and resources on the current host (due to other factors) become scarce, migration of the multitier application to another host with sufficient resources would be desirable.

This can be achieved by disabling the test performed when a vMotion is initiated that looks for connection to an internal network. (I would not recommend that this is done with Production environments!)

From a vSphere Client connected to the vCenter Server navigate to Administration >vCenter Server Settings > Advanced Settings and add config.migrate.test.CompatibleNetworks.VMOnVirtualIntranet with a value of "false".

This change does not require a restart of vCenter Server.

Obviously to change the setting back, change the value to "true".

For more detail check out the VMware Knowledgebase Article 1003832.