OKD Upgrade Stuck: StorageVersionMigration Failed

Upgrading your OKD cluster can sometimes hit snags, and one particularly frustrating issue is when the upgrade process gets stuck on StorageVersionMigration_FailedCheckCRDStoredVersions. This article delves into the specifics of this problem encountered during an upgrade from OKD 4.20.0-okd-scos.7 to v4.20.0-okd-scos.8, providing a comprehensive look at the symptoms, potential causes, and troubleshooting steps.

Understanding the Bug

The core issue manifests as a degraded console during the upgrade process. Let's break down the key indicators:

• Stuck Upgrade: The upgrade process halts, with the console showing as degraded.
• Error Message: The error message StorageVersionMigration_FailedCheckCRDStoredVersions appears, indicating a problem with storage version migrations.
• Cluster Operator Status: The console cluster operator is degraded, further confirming the issue.
• Storage Version Migrations: Interacting with storage version migrations shows ongoing processes that might not be completing successfully.

To provide more context, in the Control Plane, the upgrade process hangs at 88%, showing several operators updated, none updating, and a few waiting. This is coupled with the console operator being degraded due to StorageVersionMigrationDegraded: the server was unable to return a response in the time allotted, but may still be processing the request. These messages indicate that the system is experiencing difficulties in migrating storage versions, potentially due to timeouts or other underlying issues.

Further complicating matters, alerts start firing, indicating that the cluster operator has been degraded for an extended period. This scenario underscores the importance of promptly addressing storage version migration issues to prevent prolonged disruptions to cluster operations.

Symptoms and Observations

Here are some key symptoms observed during the upgrade:

• Console Degradation: The console operator is reported as degraded.
• Error Messages: Specific error messages related to StorageVersionMigration_FailedCheckCRDStoredVersions are present.
• Alerts Firing: Alerts related to degraded cluster operators and samples operator credential issues are triggered.
• StorageVersionMigrations: Checking existing storage version migrations reveals entries like flowcontrol-flowschema-storage-version-migration that might be contributing to the problem.

Potential Causes

Several factors can contribute to the StorageVersionMigration_FailedCheckCRDStoredVersions error:

• Resource Constraints: Insufficient resources (CPU, memory) can cause timeouts during the migration process.
• API Server Issues: Problems with the API server can hinder communication and migration completion.
• CRD Issues: Custom Resource Definition (CRD) inconsistencies or corruption can disrupt storage version migrations.
• Networking Problems: Network connectivity issues can prevent successful communication between components involved in the migration.

Troubleshooting Steps

When faced with this issue, consider the following troubleshooting steps:

1. Check Cluster Resources:

   • Ensure that the cluster has sufficient CPU and memory resources.
   • Monitor resource utilization during the migration process to identify potential bottlenecks.

2. Examine API Server Logs:

   • Inspect the API server logs for any errors or warnings related to storage version migrations.
   • Look for timeouts or other issues that might indicate API server problems.

3. Verify CRD Health:

   • Check the health and consistency of your Custom Resource Definitions (CRDs).
   • Ensure that the CRDs are correctly defined and that there are no schema inconsistencies.

4. Review Network Connectivity:

   • Verify network connectivity between the control plane nodes.
   • Ensure that there are no firewall rules or network policies blocking communication.

5. Check Storage Version Migrations:

   • List existing storage version migrations using oc get storageversionmigrations.migration.k8s.io.
   • Examine the status of each migration to identify any that are failing or stuck.

6. Manual Intervention (Caution Required):

   • As a last resort, you might consider manually deleting problematic storage version migrations. However, this should be done with extreme caution, as it can potentially lead to data loss or cluster instability. Before deleting any migrations, ensure you have a valid backup and understand the implications.
   • Use oc delete storageversionmigrations.migration.k8s.io <migration-name> to delete a specific migration.

7. Unmanaging the storage-version-migrator:

   • Unmanaging the storage-version-migrator ClusterOperator tells the Cluster Version Operator to leave the storage-version-migrator alone during upgrades. This can sometimes unblock an upgrade. Applying the patch with `oc patch clusterversion version -p '{