Calculate the cluster-wide live-migration bandwidth limit from all relevant adapters

Source facts

Microsoft requires calculating the bandwidth available across the physical adapters used by the cluster before choosing the SMB bandwidth percentage. That percentage uses the cluster’s total bandwidth even when live migration is assigned a particular cluster network. Cluster nodes must consistently use SMB for live migration to use this control. The cluster parameters distribute the chosen values to a newly added node automatically. These cluster-wide limits work on physically hosted cluster nodes, not on nodes running as virtual machines. Microsoft documentation.

Applicability

Inventory the adapters, speeds, cluster networks, and configured live-migration transport. Review how the total was calculated and distinguish this rate-limit decision from deciding which networks may carry migrations.

DSE recommendation

Write the proposed percentage and its bandwidth calculation in the change record. Ask workload and network owners to agree on the capacity reserved for concurrent activity. Preserve the original cluster values, then choose a representative migration workload and a measurement window before changing the limit.

Verification

Perform approved live migrations while measuring migration traffic and application behavior. Compare the observed usage with the intended reservation and document the number of concurrent migrations. Inspect the inherited settings when adding a test node, and revisit the calculation after a material change in adapter capacity.

Official references

Microsoft Learn: Control Live Migration SMB Bandwidth Control Cluster-wide in Windows Server and Azure Local. Source reviewed September 8, 2026.