Fixing ORA-30012: Unable to Convert Physical Standby to Snapshot Standby

 

Introduction 

I recently encountered the frustrating "ORA-30012: undo tablespace 'UNDOTBS1' does not exist or is of wrong type" while attempting to convert my Data Guard Physical Standby into a writable Snapshot Standby for an important testing cycle. In my setup, the Primary database was a RAC running on Exadata Database Service on Dedicated Infrastructure, while the Standby was a single-instance deployment on DBCS. This mixed environment introduced subtle configuration differences, and one of those differences caused the ORA-30012 failure during the snapshot conversion. In this post, I’ll walk through how I investigated the issue, identified the undo-related mismatch on the standby, and applied the correct fix to enable the Snapshot Standby conversion successfully.

Troubleshooting ORA-29771 on a DBCS Data Guard Standby

Introduction

Recently, I encountered an issue on a DBCS Data Guard standby database where the alert log reported the error ORA-29771. After seeing this error, I checked the Data Guard status and noticed that the standby had developed a significant apply lag, even though redo apply was still running.

In this blog, I’ll explain the symptoms I observed, how I investigated the cause of the ORA-29771 error, and the steps I took to restore normal standby performance.

Fixing a DBCS Startup Failure Caused by ORA-07445

 

Introduction:

Running Oracle databases on Oracle Database Cloud Service (DBCS) usually provides a stable and well-automated environment, but unexpected platform-level issues can still occur—especially when critical OS-level components are modified or removed. Recently, I encountered a serious problem where a DBCS compute node failed to start the database, and the stack repeatedly threw an ORA-07445 error during the startup process.

At first glance, the issue looked like a typical software or patch conflict, but after deeper investigation, it turned out to be something far more fundamental: the swap mount point and related configuration had been cleared or removed on the compute instance. Without an active swap device, several Oracle background processes failed during initialization, resulting in the ORA-07445 crash.

In this blog, I’ll walk you through the symptoms, diagnostic steps, and the exact solution that restored the instance.