Problem Description:
An Oracle RAC backup may fail with errors such as ORA-12537 and missing PDB$SEED tablespace metadata.
This typically occurs when one or more pluggable databases (PDBs) are not in an open state during the backup discovery phase.
Symptoms:
Backup jobs fail intermittently on one Oracle RAC node.
RMAN logs display connection and initialization errors.
Backup job fails with messages similar to:
RMAN-00571: ============================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00554: initialization of internal recovery manager package failed
RMAN-04005: error from target database:
ORA-01017: invalid username/password; logon denied
ORA-12537: TNS: connection closed
Backup failure error: Failed to construct restore view.
Tablespace error: Tablespace information not present in Metadata for PDB PDB$SEED.
Cause:
The backup failure occurred because some Pluggable Databases (PDBs), including PDB$SEED, were not in an open state when the Druva agent attempted to discover and collect tablespace metadata.
During the discovery phase, the Druva agent queries metadata from all containers (CDB and PDBs).
If a PDB is closed or restricted, the agent cannot retrieve required metadata, resulting in backup failure.
Resolution:
Step 1 – Verify PDB States
Connect to the container database (CDB) as SYSDBA.
Run the following query to check the current PDB states:
SELECT name, open_mode FROM v$pdbs;
Review the output and identify any PDBs in MOUNTED or CLOSED state.
Step 2 – Open PDB$SEED and Other PDBs
Ensure that PDB$SEED is in READ ONLY mode, as required by Oracle.
ALTER PLUGGABLE DATABASE PDB$SEED OPEN READ ONLY;Open all other application PDBs in READ WRITE mode:
ALTER PLUGGABLE DATABASE ALL OPEN;or open them individually:
ALTER PLUGGABLE DATABASE <PDB_NAME> OPEN READ WRITE;
Step 3 – Retry the Druva Backup
After confirming all required PDBs are open:
Restart the Druva Oracle backup job.
Verify that the agent successfully discovers all containers and tablespaces.
Verification:
Confirm that the backup job completes successfully in the Druva Console
Check RMAN logs for the absence of ORA-12537 and PDB$SEED metadata errors.
Run the following SQL command to confirm the current open states:
SELECT name, open_mode FROM v$pdbs;
Additional Information:
The PDB$SEED pluggable database must always remain OPEN READ ONLY for operations such as cloning and backup.
If PDB$SEED or other PDBs are left in a closed state, metadata collection will fail, preventing backups from completing.
ORA-12537 generally indicates a lost or terminated connection between the agent and the Oracle database, often triggered when PDBs are not open during query execution.