Netapp on-prem S3 storage - Size on Media vs Estimated Media Size

Hi ​@Mateusz Slezak ,

Commvault doesn’t run space reclamation automatically on cloud storage (or S3 comp.)  this is because space reclamation would incur charges for the cloud vendor, so Commvault leave this decision to the administrator to take, I believe it can be scheduled as well, In your situation, it’s recommended to run it, but take care as this would load the mount path,

You can check Space Reclamation (SR) job history,
Viewing the DDB Space Reclamation Job History at the CommCell Level

Please refer to: Performing a Space Reclamation Operation on Deduplicated Data


Adding more information from Arlie below,
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Space Reclamation and Micro Pruning on S3-Compatible Storage

Micro Pruning

• Runs automatically as data meets retention.
• Marks data for deletion in the deduplication database (DDB) but does not physically reclaim disk space.
• Should always be enabled for ongoing logical cleanup.

Space Reclamation

• Not scheduled by default for S3-compatible storage; must be run manually or scheduled by the administrator.
• Physically compacts and deletes unused blocks, freeing up disk space and reducing fragmentation.
• Essential when there is a significant gap between "Size on Disk" and "Estimated Media Size" (e.g., >20–30%), or when storage utilization is high.
• Micro pruning alone is not sufficient for reclaiming physical space—space reclamation is required.

Automatic Triggers

• Space reclamation is not triggered automatically when data meets retention.
• Micro pruning is automatic, but space reclamation must be initiated by the user.

Best Practices

• Monitor storage metrics regularly.
• Run space reclamation periodically or when fragmentation is high.
• Schedule space reclamation during maintenance windows to minimize impact.
• Be aware of potential cloud costs due to increased read/write operations.

Drawbacks and Considerations

• Can be I/O-intensive and may impact MediaAgent/storage performance during the job.
• May incur additional costs on S3/cloud storage due to increased operations.
• Should not be run concurrently with restore jobs from the same mount path to avoid restore failures.
• Job duration can be significant, especially on large or highly fragmented storage pools.