Windows Server Semi-Annual Channel , Windows Server , Windows Server R2, Windows Server Cluster-Aware Updating CAU is a feature that coordinates software updates on all servers in a failover cluster in a way that doesn't impact the service availability any more than a planned failover of a cluster node. For some applications with continuous availability features such as Hyper-V with live migration, or an SMB 3.
Specifically, CAU orchestration ensures that suspending each cluster node waits for the underlying clustered storage space to be healthy. Is CAU limited to specific clustered applications? CAU is agnostic to the type of the clustered application.
As such, CAU can coordinate updating for any clustered application that is configured in a Windows Server failover cluster. Note Currently, the following clustered workloads are tested and certified for CAU: Can CAU apply limited distribution release updates? However, CAU includes a second plug-in that you can select to apply hotfix updates.
This hotfix plug-in can also be customized to apply non-Microsoft driver, firmware, and BIOS updates. Can I use CAU to apply cumulative updates? Can I schedule updates? CAU supports the following updating modes, both of which allow updates to be scheduled: Self-updating Enables the cluster to update itself according to a defined profile and a regular schedule, such as during a monthly maintenance window. You can also start a Self-Updating Run on demand at any time. To enable self-updating mode, you must add the CAU clustered role to the cluster.
The CAU self-updating feature performs like any other clustered workload, and it can work seamlessly with the planned and unplanned failovers of an update coordinator computer. Remote-updating is the default updating mode for CAU. You can use Task Scheduler to run the Invoke-CauRun cmdlet on a desired schedule from a remote computer that is not one of the cluster nodes. Can I schedule updates to apply during a backup? CAU doesn't impose any constraints in this regard.
However, performing software updates on a server with the associated potential restarts while a server backup is in progress is not an IT best practice.
CAU is a tool that coordinates software updates on a cluster node, and Configuration Manager also performs server software updates. It's important to configure these tools so that they don't have overlapping coverage of the same servers in any datacenter deployment, including using different Windows Server Update Services servers.
This ensures that the objective behind using CAU is not inadvertently defeated, because Configuration Manager-driven updating doesn't incorporate cluster awareness. Do I need administrative credentials to run CAU?
For running the CAU tools, CAU needs administrative credentials on the local server, or it needs the Impersonate a Client after Authentication user right on the local server or the client computer on which it is running. However, to coordinate software updates on the cluster nodes, CAU requires cluster administrative credentials on every node.
Although the CAU UI can start without the credentials, it prompts for the cluster administrative credentials when it connects to a cluster instance to preview or apply updates. Can I script CAU? CAU comes with PowerShell cmdlets that offer a rich set of scripting options.
What happens to active clustered roles? Clustered roles formerly called applications and services that are active on a node, fail over to other nodes before software updating can commence. CAU orchestrates these failovers by using the maintenance mode, which pauses and drains the node of all active clustered roles. When the software updates are complete, CAU resumes the node and the clustered roles fail back to the updated node. This ensures that the distribution of clustered roles relative to nodes stays the same across the CAU Updating Runs of a cluster.
How does CAU select target nodes for clustered roles? The clustering API implementation selects the target nodes by relying on internal metrics and intelligent placement heuristics such as workload levels across the target nodes. Does CAU load balance the clustered roles? CAU doesn't load balance the clustered nodes, but it attempts to preserve the distribution of clustered roles. When CAU finishes updating a cluster node, it attempts to fail back previously hosted clustered roles to that node.
Thus in the absence of unplanned failovers and preferred owner settings, the distribution of clustered roles should remain unchanged. How does CAU select the order of nodes to update? By default, CAU selects the order of nodes to update based on the level of activity. The nodes that are hosting the fewest clustered roles are updated first. However, an administrator can specify a particular order for updating the nodes by specifying a parameter for the Updating Run in the CAU UI or by using the PowerShell cmdlets.
What happens if a cluster node is offline? The administrator who initiates an Updating Run can specify the acceptable threshold for the number of nodes that can be offline.
Therefore, an Updating Run can proceed on a cluster even if all the cluster nodes are not online. Can I use CAU to update only a single node? CAU is a cluster-scoped updating tool, so it only allows you to select clusters to update.
If you want to update a single node, you can use existing server updating tools independently of CAU. However, when a subsequent CAU Updating Run is launched, updates that were installed through non-CAU methods are appropriately considered to determine the additional updates that might be applicable to each cluster node.
CAU offers the following dimensions of flexibility to suit enterprise customers' unique IT process needs: The pre-update script runs on each cluster node before the node is paused.
The post-update script runs on each cluster node after the node updates are installed. You must also enable PowerShell remoting on the cluster nodes. Advanced Updating Run options The administrator can additionally specify from a large set of advanced Updating Run options such as the maximum number of times that the update process is retried on each node.
CAU ships with two default plug-ins: If an enterprise has unique needs that cannot be met with these two plug-ins, the enterprise can build a new CAU plug-in according to the public API specification. For information about configuring and customizing CAU plug-ins to support different updating scenarios, see How Plug-ins Work.
How can I export the CAU preview and update results? CAU offers export options through the command-line interface and through the UI. Copy the report results from the Preview updates screen. CSV Copy the report results from the Generate report screen. CSV Export the report results from the Generate report screen. CAU is installed as follows: Does CAU need components running on the cluster nodes that are being updated? CAU doesn't need a service running on the cluster nodes.
This component is installed with the Failover Clustering feature. To enable self-updating mode, the CAU clustered role must also be added to the cluster. If you already own a System Center license, you can continue to use VMM to update Hyper-V clusters because it offers an integrated management and software updating experience.
Can I use remote-updating on a cluster that is configured for self-updating? A failover cluster in a self-updating configuration can be updated through remote-updating on-demand, just as you can force a Windows Update scan at any time on your computer, even if Windows Update is configured to install updates automatically.
However, you need to make sure that an Updating Run is not already in progress. Can I reuse my cluster update settings across clusters? CAU supports a number of Updating Run options that determine how the Updating Run behaves when it updates the cluster.
These options can be saved as an Updating Run Profile, and they can be reused across any cluster. We recommend that you save and reuse your settings across failover clusters that have similar updating needs.
Where is the CAU plug-in specification?