With auto-scaling, the Commvault software deploys access nodes in Azure regions only when they are needed, and then uses power management (enabled by default) to power off and decommission the access nodes soon after you use them. Auto-scaling, combined with power management, can reduce the cost of using Azure access nodes to back up VMs.
Also, you can perform backup copy operations using auto-scaling.
Authentication
You can configure auto-scaling only for hypervisors that use traditional authentication with Azure Active Directory. If you have a hypervisor that uses managed identity authentication and you want to use it for auto-scaling, you can change the authentication method for the hypervisor to traditional.
Creation and Decommissioning of Access Nodes
Number of Access Nodes That Are Created
The number of access nodes that are required increases or decreases based on the amount of data you back up and the settings you configure for auto-scaling.
The Commvault software determines the number of access nodes to create based on the following characteristics:
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The Recovery Point Objective (RPO)
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The throughput rate
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The number of data readers that are configured for the VM group
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The Maximum number of access nodes setting in the Auto scale settings dialog box
Important
To increase the number of access nodes, change the Maximum number of access nodes setting instead of changing the number of data readers per access node.
Decommissioning of Access Nodes
Automatically scaled access nodes shut down after they are idle for 5 minutes. If an access node is shut down when a job request is initiated, then the access node is powered on and used. If no activity occurs for an additional 30 minutes on the access node that is shut down, then the access node is deleted from both the Command Center and the Azure portal.
If there are multiple access nodes in use during a backup operation, and some access nodes are backing up VMs, while other access nodes have completed backups for VMs (or are otherwise idle), the idle access nodes are shut down after 5 minutes. This can help reduce the compute cost.
If you manually remove an access node from the server group, it is not deleted from the Command Center or the Azure portal. You must add the access node back to the server group and allow the automatic process to delete the access node.
Log Files
To troubleshoot failed backup operations, you can view the log files for automatic scaling at the following location on the CommServe server: Commvault\ContentStore\iDataAgent\JobResults\CV_JobResults\AutoScale.