Skip Kernel Soft Reboot on certain servers To use Kernel Soft Reboot with a specific Cluster-Aware Updating run, use the optional AttemptSoftReboot parameter when using CAU PowerShell cmdlets, such as in the following examples. Option 2: Use Kernel Soft Reboot with individual CAU runs Resetting this private property to any other value than 1 or deleting the property entirely will disable Kernel Soft Reboot on the cluster.

In Azure Stack HCI, version 21H2, you can use PowerShell to set up and manage Kernel Soft Reboot for your Azure Stack HCI cluster.

Enable Kernel Soft Reboot with Cluster-Aware Updating using PowerShell Currently, you can use Kernel Soft Reboot optionally with the Cluster-Aware Updating WindowsUpdate plugin for Quality Updates and Hotfix plugin for MSI/MSU/EXEs files only. When to use Kernel Soft RebootĪs this feature bypasses the lengthy and traditional reboot BIOS/FIRMWARE initialization, you can only use Kernel Soft Reboot for updates that do not require a firmware/BIOS initialization. Take a few minutes to watch the video comparing the performance of a normal reboot to a Kernel Soft Reboot on an idle server. As server resources such as available memory and drives increase, so does the time savings. The amount of time saved will be proportional to the memory and size of the server. Kernel Soft Reboot improves reboot performance by streamlining the operating system flow, minimizing the amount of data to be resynced and therefore reducing the overall cluster update time. The longer it takes to reboot a server, the more data must be resynced, and the longer the overall cluster update time. Even though Cluster-Aware Updating (CAU) automates many of these tasks, when the cluster resumes, any new data written while under maintenance mode still needs to be resynced. Traditionally, servicing a cluster (for example, applying software updates) requires putting each server in maintenance node, evacuating the server, installing updates, rebooting if necessary, and then repeating the process for every server in the cluster.

This topic explains when to use a KSR over a normal reboot and provides instructions on using this feature on Azure Stack HCI.

You can use it when updating the cluster to reboot the servers faster than a normal reboot. New in Azure Stack HCI, version 21H2, Kernel Soft Reboot (KSR) is a premium feature available on all Azure Stack HCI integrated systems. Applies to: Azure Stack HCI, version 21H2

Increase kernel stack size