Add PauseRack docs

Author: vivekjMSFT

articles/operator-nexus/howto-cluster-runtime-upgrade-with-pauserack-strategy.md

@@ -0,0 +1,66 @@
+---
+title: "Azure Operator Nexus: Runtime upgrade with rack pause strategy"
+description: Learn to execute a cluster runtime upgrade for Operator Nexus with a pause rack strategy
+author: vivekjMSFT
+ms.author: vija
+ms.service: azure-operator-nexus
+ms.topic: how-to
+ms.date: 08/16/2024
+# ms.custom: template-include
+---
+
+# Upgrading cluster runtime with a pause rack strategy
+
+This how-to guide explains the steps to execute a cluster runtime upgrade with pasue rack strategy. Executing cluster runtime upgrade with "PauseRack" strategy will update a single rack in a cluster and then pause to wait for confirmation before moving to the next rack. All existing thresholds will still be honoried with pause rack strategy.
+
+## Prerequisites
+
+Please follow the steps mentioned in prerequistie section of [Upgrading cluster runtime from Azure CLI](./howto-cluster-runtime-upgrade.md)
+
+> **Note:**
+> Upgrades with the Rack Pause strategy will only work after the management bundle (CMBU) has been upgraded to 3.8 or greater.
+
+## Procedure
+
+1. Enable Rack Pause upgrade strategy on a Nexus cluster
+
+    > **Note:**
+    > choose threshold value as desired.
+
+    Example:
+
+    ```azurecli
+    az networkcloud cluster update --name "clusterName" --resource-group "resourceGroupName" --update-strategy \
+        strategy-type="PauseRack" \
+        wait-time-minutes=0 \
+        <threshold values as desired>
+    ```
+
+2. Confirm that the cluster resource JSON in the JSON View reflects the rack pause upgrade strategy.
+
+```shell
+az networkcloud cluster show --cluster-name "clusterName" --resource-group "resourceGroupName"
+```
+
+:::image type="content" source="media/runtime-upgrade-cluster-pause-rack-strategy.png" alt-text="Runtime upgrade strategy property details":::
+
+3. Trigger runtime bundle upgrade as usual from Azure portal / CLI. for reference [Upgrading cluster runtime from Azure CLI](./howto-cluster-runtime-upgrade.md)
+
+4. Once Rack 1 has completed, the runtime upgrade will pause, awaiting user action to resume the runtime upgrade for Rack 2.
+
+:::image type="content" source="media/runtime-upgrade-cluster-paused.png" alt-text="Paused Runtime Upgrade":::
+
+5. To resume the runtime upgrade, execute the following `az networkcloud` cli command to trigger the continue upgrade version action.
+
+```shell
+az networkcloud cluster continue-update-version \
+    --subscription=$SUBSCRIPTION \
+    --resource-group=$RESOURCE_GROUP \
+    --cluster-name=$CLUSTER_NAME
+```
+
+6. Continue repeating step 5 for each rack until all racks have been upgraded to the latest runtime bundle.
+
+## Related content
+
+- [Upgrading cluster runtime from Azure CLI](./howto-cluster-runtime-upgrade.md)