Problem Description
Oracle RMAN backups to the Phoenix Backup Store (PBS) fail during the backup validation stage, even though the database and RMAN configurations are correct. The backup process exits before RMAN execution begins, and manual RMAN backups do not proceed as expected.
Traceback
The following message is observed in the RMAN log during the pre-backup check:
Validating backup request Response from Phoenix Backup Store: { "error_code": 0, "error_msg": "", "result": { "is_reached_max_snapshots": true, "is_version_correct": true, "message": "", "mount_name": "<DATABASE_MOUNT>" } } Validation for phoenix backup failed... exitingCause
The backup failure occurs because the maximum allowed number of pending ZFS snapshots has been reached on the Phoenix Backup Store mount.
Detailed Cause Explanation
Disabled Backupsets: The backupset was previously disabled, which completely blocks snapshot uploads to the Druva Cloud.
Upload Backlog Buffering: Phoenix Backup Store allows only a limited number of snapshots to remain in the "Pending to Upload to Cloud" state simultaneously.
Default Limitations: The default maximum allowed pending snapshots per mount is 5.
Validation Block: When manual or scheduled RMAN backups are triggered while pending snapshots sit at this threshold, PBS validation purposely fails. This behavior protects the local PBS storage from snapshot backlog, performance degradation, and storage overload.
Resolution
Follow these steps to resolve Oracle RMAN backup validation failures caused by snapshot limits:
1. Re-enable the Backupset
If the backupset was explicitly or accidentally disabled:
Log in to the Druva Cloud Platform Console.
Navigate to your Enterprise Workloads -> Oracle section.
Locate the affected backupset and toggle its status back to Enabled.
This action allows the Phoenix Backup Store to resume snapshot queue processing.
2. Allow Pending Snapshots to Upload
Phoenix Backup Store processes and uploads snapshots sequentially.
Allow time for the existing backlog of pending snapshots to upload safely to the cloud.
Do not trigger manual RMAN backups repeatedly while snapshots are at their maximum limit, as this resets validation failures.
Monitor upload progress directly via the Jobs tab in the Druva Console.
3. Retry the RMAN Backup
Once the cloud synchronization finishes and the pending snapshot count falls below the threshold:
Re-run your manual RMAN backup script.
The PBS pre-validation API will now return
is_reached_max_snapshots: false, and the backup will proceed normally.
Expected Outcome
Manual RMAN backups finish without pre-execution drops.
PBS validation passes successfully.
Database mount storage queues normalize.
Configuration Details
MAX_ORACLE_SNAPSHOTS Parameter
The MAX_ORACLE_SNAPSHOTS parameter defines the maximum number of point-in-time ZFS snapshots allowed to sit in a "Pending to Upload to Cloud" state per PBS mount.
⚠️ Note: This configuration restricts upload queue backlogs; it does not impact your local RMAN retention settings configured on the PBS.
When the snapshot count hits this designated ceiling, PBS deliberately blocks incoming RMAN requests until the queue clears.
Default Values & Paths
Default Value: 5
Configuration Paths by Agent Version:
Agent Version v6.x:
/etc/Phoenix/Phoenix.cfgAgent Version v7.x:
/etc/Phoenix/Config.yaml(or respective enterprise config directories)
⛔ Caution: Modifying or increasing this limit should only be handled under guidance from Druva Support. Higher limits risk inflating local storage consumption and lengthening synchronization queues during network bottlenecks.
Recommendations & Best Practices
Avoid disabling backupsets for long operational windows.
Regularly monitor snapshot upload activities using administrative dashboards.
Clear out pending backlogs prior to executing intensive manual database maintenance or manual backups.
Coordinate on-demand manual backups during low production hours to avoid upload concurrency blocks.