reimage first draft

Author: wtnlee

articles/virtual-wan/how-to-network-virtual-appliance-reimage.md

@@ -0,0 +1,62 @@
+---
+title: 'Azure Virtual WAN: reimage a Network Virtual Appliance (NVA) in the hub'
+description: Learn how to reimage a Network Virtual Appliance in the Virtual WAN hub.
+author: wtnlee
+ms.service: azure-virtual-wan
+ms.topic: how-to
+ms.date: 1/28/2025
+ms.author: wellee
+# Customer intent: As someone who has deployed a Network Virtual Appliance (NVA) in Virtual WAN, I want to restart the NVAs running in Virtual WAN.
+---
+
+# How to reimage a Network Virtual Appliance in an Azure Virtual WAN hub
+
+The following article shows you how to reimage Network Virtual Appliances (NVAs) deployed in the Virtual WAN hub. This article doesn't apply to NVAs deployed as Virtual Machines or Virtual Machine Scale Sets in a Virtual Network connected to Virtual WAN hubs. This article also doesn't apply to SaaS solutions deployed in the Virtual WAN hub.
+
+## Operation overview
+
+> [!NOTE]
+> The reimage operation results in downtime for the reimaged instance as it requires the NVA instance to restart and requires reconfiguration of the reimaged NVA instance. Reimage is typically used for in scenarios where a NVA VM instance is used as a last-resort recovery mechanism when an NVA instance is inaccessible, unreachable or otherwise non-functioning.  The reimage operation is targeted to one NVA instance and **does not** impact other NVA VM instances in the same deployment.  
+
+Reimage is an option is executed on Virtual WAN NVA Virtual Machine (VM) instances. The reimage operation removes the existing operating system (OS) disk associated with an NVA VM and replaces it with a new OS disk. The new OS disk is deployed from Azure Marketplace and runs the same initial software version that the NVA was deployed with. For example, if your NVA device was deployed with NVA OS version 10, and you subsequently upgraded the NVA version to version 12 as part of an out-of-band upgrade workflow initiated from the command line or NVA orchestration software, Azure Virtual WAN reimages your NVA instance to version 10 and not version 12. As a result, you may have to manually execute an OS software version upgrade after performing the reimage operation.  
+
+The reimage operation also removes any existing NVA configurations stored on the OS disk and re-runs the cloudinit script that was specified when the NVA was initially deployed.
+  
+## Prerequisites
+
+Verify that your deployment meets the following prerequisites before attempting to reimage the NVA instances:
+* A Network Virtual Appliance is deployed in a Virtual WAN hub. For more information on NVAs deployed in the Virtual WAN hub, see [Integrated NVA documentation](../../articles/virtual-wan/about-nva-hub.md).
+* The Network Virtual Appliance's provisioning state is "Succeeded."
+
+## Considerations
+
+* Only one instance of a Virtual WAN NVA can be reimaged at a time from Azure portal. If you need to reimage multiple NVA instances, wait for an NVA instance to finish reimaging before proceeding to the next instance. 
+* You can only restart an NVA if the provisioning state of the NVA is succeeded. Wait for any ongoing operations to finish before reimaging an NVA instance.  
+* You can't select the OS version Azure platform reimages your NVA.
+* IP addresses for NVA instances are preserved during reimage operations.
+
+## Reimage the NVA
+
+1. Navigate to your Virtual WAN hub and select **Network Virtual Appliances** under Third-party providers.
+    :::image type="content" source="./media/network-virtual-appliance-reimage/find-network-virtual-appliance.png"alt-text="Screenshot showing how to find NVA in Azure portal."lightbox="./media/network-virtual-appliance-reimage/find-network-virtual-appliance.png":::
+2. Select **Manage configurations** for the NVA you want to restart.
+    :::image type="content" source="./media/network-virtual-appliance-reimage/manage-configurations.png"alt-text="Screenshot showing how to manage configurations for NVA."lightbox="./media/network-virtual-appliance-reimage/manage-configurations.png":::
+3. Select **Instances** under Settings.
+    :::image type="content" source="./media/network-virtual-appliance-reimage/find-instances.png"alt-text="Screenshot showing instance level settings for NVA."lightbox="./media/network-virtual-appliance-reimage/find-instances.png":::
+4. Select the instance of the NVA you want to restart.
+    :::image type="content" source="./media/network-virtual-appliance-reimage/select-instance.png"alt-text="Screenshot showing how to select an NVA instance."lightbox="./media/network-virtual-appliance-reimage/select-instance.png":::
+5. Select **Reimage**.
+    :::image type="content" source="./media/network-virtual-appliance-reimage/execute-reimage.png"alt-text="Screenshot showing how to reimage an NVA instance."lightbox="./media/network-virtual-appliance-restart/execute-reimage.png":::
+6. Read the disclosure on the screen and note the OS software version that the post-reimage NVA instance will be running. Confirm the reimage by selecting **Yes**. 
+    :::image type="content" source="./media/network-virtual-appliance-reimage/confirm-reimage.png"alt-text="Screenshot showing how to confirm you want to reimage an NVA instance."lightbox="./media/network-virtual-appliance-reimage/confirm-reimage.png":::
+
+## Troubleshooting
+
+The following section describes common issues associated with restarting an NVA instance.
+
+* **NVA provisioning state needs to be successful**: If the NVA is in an "Updating" or "Failed" state, you can't execute reimage operations on the NVA. Wait for any existing operation on the NVA to finish before trying to reimage again.
+* **Reimage already in progress**: Multiple concurrent restart operations aren't supported. If there's a reimage operation running on the NVA resource already, wait for the operation to finish before attempting to restart a different instance.
+* **Operations on the NVA are not allowed at this time. Please try again later**: Try the reimage operation again in 15-30 minutes.
+* **The NVA operation failed due to an intermittent error**: Try the reimage operation again.
+* **Instance provided does not exist**: Reimage API request body references instance IDs. To determine which instance IDs are currently in use, navigate to **Instances** in Azure Portal for your NVA resource. Virtual WAN names NVA instances with the following naming convention: "nvaresourcename_**instanceID**". In the example below, valid instance IDs are "0" and "1".
+ :::image type="content" source="./media/network-virtual-appliance-reimage/instance-names.png"alt-text="Screenshot showing how to check instance IDs used for reimage."lightbox="./media/network-virtual-appliance-reimage/instance-names.png":::