Merge pull request #1783 from redis/RDSC-3785-add-note-for-rdi-1.8.0-upgrade-known-issue

RDSC-3785: Document known issue for RDI upgrade from < 1.8.0 to >= 1.8.0

Author: andy-stark-redis

content/integrate/redis-data-integration/installation/upgrade.md

@@ -82,6 +82,26 @@ If there is an active pipeline, upgrade RDI on the active VM first.
 This will cause a short pipeline downtime of up to two minutes. 
 Afterwards, upgrade RDI on the passive VM. This will not cause any downtime.
 
+{{< warning >}}
+When upgrading from RDI < 1.8.0 to RDI >= 1.8.0 in a VM HA setup, both RDI instances may incorrectly consider themselves active after the upgrade. This occurs because the upgrade process doesn't change the cluster id value from its default `cluster-1`, causing both clusters to assume they are the active cluster.
+
+**Symptoms:**
+
+- The upgraded passive node will start collector and processor components
+- Collector may enter a crash loop as it fails to connect to the source
+- Both clusters will restart in a loop
+
+**Workaround:**
+
+After upgrading, manually set a unique cluster ID for one of the installations (preferably on the passive instance):
+
+1. Locate the RDI configuration file on the VM host. The file is typically located at `/etc/rdi/rdi-sys-config.yaml`.
+2. Open the configuration file in a text editor. For example:
+
+   ```bash
+   sudo nano /etc/rdi/rdi-sys-config.yaml
+{{< /warning >}}
+
 ## Upgrading a Kubernetes installation
 
 Follow the steps below to upgrade an existing

content/integrate/redis-data-integration/release-notes/rdi-1-8-0.md

@@ -87,3 +87,29 @@ The RDI operator has been significantly enhanced in the following areas:
 ## Limitations
 
 RDI can write data to a Redis Active-Active database. However, it doesn't support writing data to two or more Active-Active replicas. Writing data from RDI to several Active-Active replicas could easily harm data integrity as RDI is not synchronous with the source database commits.
+
+## Known Issues
+
+### High Availability upgrade issue
+
+When upgrading from RDI < 1.8.0 to RDI >= 1.8.0 in an HA setup, both RDI instances may incorrectly consider themselves active after the upgrade. This occurs because the upgrade process doesn't update the `rdi:ha:lock` value from the legacy `cluster-1` identifier, causing both clusters to assume they are the active cluster.
+
+**Symptoms:**
+
+- The upgraded passive node will start collector and processor components
+- Collector may enter a crash loop as it fails to connect to the source
+- Both clusters will restart in a loop
+
+**Workaround:**
+
+After upgrading, manually set a unique cluster ID for one of the installations by editing the configmap:
+
+```bash
+kubectl edit cm -n rdi rdi-sys-config
+```
+
+Then add the following line to distinguish between the clusters:
+
+```bash
+RDI_CLUSTER_ID: cluster-2
+```