Note
Access to this page requires authorization. You can try signing in or changing directories.
Access to this page requires authorization. You can try changing directories.
Cluster-wide parameters enable you to reserve network bandwidth for SMB between failover cluster nodes. With automatic configuration of the SMB bandwidth limits for live migration, administrators no longer need to analyze and configure these limits on individual cluster nodes. This article shows you how to configure cluster-wide Live Migration SMB Bandwidth control in Windows Server and Azure Local.
When you configure Hyper-V to use SMB for Live Migration, configuring the SMB bandwidth limits is critical to the reliability and availability of the system. If live migration over SMB consumes too much bandwidth, storage and cluster network traffic could be delayed or dropped, affecting the system and hosted services.
Tip
If you're using Azure Local, use Network ATC for all your host networking requirements, including SMB Bandwidth management, live migrations, and much more. To learn more about using Network ATC to manage SMB bandwidth limits, see Manage Network ATC.
Prerequisites
Before you can configure SMB bandwidth control for Live Migration, you must have the following prerequisites.
A failover cluster running Windows Server or Azure Local. To learn more about creating a failover cluster, see Create a failover cluster for Windows Server and Create an Azure Local cluster.
Each cluster node must have the Hyper-V Server role installed and has Live Migration configured. For more information, see Install the Hyper-V role on Windows Server on how to get started.
Each cluster node must have the FS-SMBBW Windows Feature installed.
Important
After you install the SMB Bandwidth Limit feature on a cluster node, SMB bandwidth is limited to the default of 25% of the nodes total bandwidth.
Each cluster node must have 2022-09 Cumulative Update for Microsoft server operating system version 21H2 or later installed. For more information, see KB5017381 for Windows Server 2022 and KB5017382 for Azure Stack HCI OS, version 21H2.
An account that is a member of the Administrators group, or equivalent.
Calculate bandwidth limit
Before you can configure a bandwidth limit for SMB, you must calculate the total bandwidth to be reserved for SMB traffic across all physical network adapters used by the cluster. The bandwidth limit uses a percentage of the total bandwidth available to the cluster, even when Live Migration is configured to use a specific cluster network.
The default SMB bandwidth limit factor is 2500 (25%) of the total bandwidth available to the cluster node.
You should consider how much bandwidth is available to the cluster and how much bandwidth is needed for other cluster traffic, and other traffic using the same cluster network enabled for Live Migration.
To calculate the bandwidth limit factor, follow the steps.
Sum the connection speed of all network adapters in one of your clusters nodes to calculate the total bandwidth for a node.
Important
Cluster nodes should have the same number of network adapters across all nodes in the cluster. The connected network adapters should also be connected at the same speeds as the other nodes in the cluster. If the cluster nodes are consistent, the bandwidth limit is calculated differently on those nodes.
Determine how much bandwidth you wish to reserve.
Calculate your SMB bandwidth limit factor using the following formula.
If you already know the percentage of bandwidth you wish to reserve, times this value by 100.
The following example uses the formula to calculate the bandwidth limit for a cluster with four nodes. Each node has four 10GB network adapters, with two cluster networks with two adapters each. Only one cluster network has Live Migration enabled. The two network adapters used for Live Migration are also used for other cluster traffic and Live Migration shouldn't consume more than 10GB or 50% of the cluster network.
The bandwidth limit is calculated as a percentage of the total bandwidth available to the cluster. The total bandwidth is 40GB and the SMB Live Migration reservation needs to be 10GB. Therefore, the SMB bandwidth limit factor is 2500, or 25%, as shown in the following example.
Configure Live Migration performance options
When you use Hyper-V in a cluster, configure the cluster nodes consistently. To use the SMB bandwidth limit, configure the cluster nodes to use SMB for Live Migration. For more information about Live Migration performance options, see Virtual Machine Live Migration Overview.
To configure the Live Migration performance options, select the relevant method and follow the steps.
Here's how to set the SMB performance option using the user interface.
Open Hyper-V Manager.
In the left navigation pane, select the cluster node.
In the right pane, select Hyper-V Settings.
In the left navigation pane, expand Live Migrations, then select Advanced Features.
In the right pane, select the SMB performance option.
Select OK to save the changes.
Repeat these steps for each cluster node.
Configure Live Migration network selection
Optional: When configuring SMB bandwidth limits for Live Migration, you might also want to configure which cluster networks can be used for Live Migration settings.
The default Live Migration settings set the cluster network used for cluster communications, CSV, and Storage Spaces Direct at the lowest preference. The default setting keeps Live Migration network traffic away from the same network the cluster uses to communicate between nodes. For more information about network prioritization and traffic isolation in a cluster, see the following articles.
To configure the Live Migration network selection, select the relevant method and follow the steps.
Here's how to set the Live Migration network selection using the user interface.
Open Failover Cluster Manager.
In the left navigation pane, expand the cluster.
Right-click Networks, then select Live Migration Settings.
In the Live Migration Settings dialog, select the cluster networks to use for Live Migration by checking or unchecking the required networks.
Select OK to save the changes.
Configure cluster-wide SMB bandwidth limits
Set the cluster-wide SMB bandwidth limits by using the SetSMBBandwidthLimit and
SetSMBBandwidthLimitFactor cluster parameters. When you add a new node to the cluster, it automatically uses
the cluster-wide values.
To apply the cluster-wide SMB bandwidth limits, follow the steps using PowerShell.
Important
The cluster-wide bandwidth limits apply only if the cluster nodes run on physical
hardware. They don't take effect if the nodes run inside of virtual
machines.
Sign in to one of the cluster nodes.
Open a PowerShell prompt as an administrator.
To check the current values of the
SetSMBBandwidthLimitandSetSMBBandwidthLimitFactorcluster parameters, use the following command.Get-Cluster | FL SetSMBBandwidthLimit,SetSMBBandwidthLimitFactorSet the SMB bandwidth limit factor with the following command using the value you calculated in the Calculate bandwidth limit section. For example, the following command sets the SMB bandwidth limit factor to 3000 (30%).
Get-Cluster | %($_.SMBBandwidthLimitFactor=3000)To enable or disable the cluster-wide SMB bandwidth limits, use the following relevant command.
# Disabled the SMB bandwidth limit Get-Cluster | %($_.SMBBandwidthLimit=0) # Enable the SMB bandwidth limit (default setting) Get-Cluster | %($_.SMBBandwidthLimit=1)
Next steps
Now you've configured cluster-wide Live Migration SMB bandwidth control here are some resources to learn more.