Data Domain: Will a Cleaning Cycle be Beneficial
Summary: This article explains how to determine whether running a filesystem cleaning operation on a Data Domain system will reclaim usable space. Cleaning removes physical storage consumed by deleted data that is not being referenced and has not yet been reclaimed by the system. ...
Instructions
1. Background: What Cleaning Does
A cleaning operation reclaims the physical space used by deleted objects. Even when backup applications expire images or when data is deleted manually:
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- Deduplicated segments referencing other files remain, but
- Unique segments marked for deletion continue to occupy space
- Space is not physically released until cleaning completes
Cleaning may be beneficial when any of the following occurred since the last completed cleaning cycle:
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- Backup application expired or deleted data
- Data was deleted on NFS/CIFS shares
- Snapshots were expired or removed
- Replication contexts were broken and had accumulated lag
- Recommended Action: In general, the once-per-week (default) cleaning schedule is best practice; manual cleaning cycles should be limited and justified by the criteria listed above.
2. Check When Cleaning Last Completed.
Use:
filesys clean status
This shows whether cleaning has run recently and whether a cycle is currently active.
3. Determine Whether Cleanable Space Exists.
Check estimated reclaimable space with:
filesys show space
The Cleanable GiB value provides an estimate of the potential space that may be reclaimed.
Important:
Cleanable GiB is an estimate. Actual reclaimed space may vary.
For details, see: Data Domain: Cleanable Size is an Estimate
4. Start Cleaning Manually (If Needed)
If cleanable space is significant or recent data deletion indicates a benefit, start cleaning manually:
filesys clean start
5. Adjusting the Cleaning Throttle
Guidance on modifying cleaning throttle settings is available in: