12.2. Live Migration Prerequisites

Live migration is used to seamlessly move virtual machines to support a number of common maintenance tasks. It is important to ensure that your Red Hat Enterprise Virtualization environment is correctly configured to support live migration well in advance of needing to use it.
At a minimum for successful live migration of virtual machines to be possible:
  • The source and destination host must both be members of the same cluster, ensuring CPU compatibility between them.
  • The source and destination host must have a status of Up.
  • The source and destination host must have access to the same virtual networks and VLANs.
  • The source and destination host must have access to the data storage domain on which the virtual machine resides.
  • There must be enough CPU capacity on the destination host to support the virtual machine's requirements.
  • There must be enough RAM on the destination host that is not in use to support the virtual machine's requirements.
In addition, for best performance, it is recommended that the storage and management networks should be split to avoid network saturation. Virtual machine migration involves transferring large amounts of data between hosts.
Live migration is performed using the management network. Each live migration event is limited to a maximum transfer speed of 30 MBps, and the number of concurrent migrations supported is also limited by default. Despite these measures concurrent migrations do have the potential to saturate the management network. It is recommended that separate logical networks are created for storage, display, and Virtual Machine data to minimize the risk of this occurring.