Warm Migration Can Fail With an Unknown migration failure Message

Bug ID 6904238: In rare circumstances, you might see a warm migration operation fail with the following message:

Unknown migration failure

The ldmd log file on the source machine shows the following message:

warning: Failed to read feasibility response type (9) from
target LDoms Manager

This failure can occur when there is a problem migrating the runtime state of the logical domain channels of the guest. This problem has occurred when the migrating domain has an unplumbed virtual network interface or has a sparse memory configuration.

Workaround: If the migrating domain has one or more unplumbed virtual network interfaces, plumb them. If the problem persists, shut down the domain and perform a cold migration.