Windows Server · medium · Storage, SAN & file services

Data Deduplication jobs fail or stop reclaiming space

The jobs are not running, cannot finish inside their window, or the data is not eligible for deduplication in the first place.

What you see

Savings stay at zero or stop growing, and the deduplication jobs show as failed or never scheduled.

What is actually wrong

Files younger than the minimum age, excluded types, jobs with too little memory, or a schedule window too short to complete on a large volume.

Codes and articles

Event 8213Event 4100Optimization jobGarbageCollectionScrubbingdedup savings zero

The fix

Check eligibility, then the schedule

Elevated PowerShell45 minuteslow riskreversible

Savings are not what is expected.

Check the status and what has actually been optimised.

PowerShell

Get-DedupStatus | Format-List Volume,Capacity,SavedSpace,SavingsRate,OptimizedFilesCount,InPolicyFilesCount,LastOptimizationResult

Compare InPolicyFilesCount against the total. A low number means the files are not eligible, not that deduplication is failing.
PowerShell
```
Get-DedupVolume | Format-List Volume,MinimumFileAgeDays,ExcludeFileType,ExcludeFolder,UsageType
```
The default minimum file age is three days, and several file types are excluded outright. A volume of files written yesterday will show zero savings and nothing is wrong with it.
Adjust the minimum age if the workload justifies it.
PowerShell
```
Set-DedupVolume -Volume E: -MinimumFileAgeDays 1
```

Check the job schedule and whether jobs are completing inside their window.

PowerShell

Get-DedupSchedule | Format-Table Name,Type,Enabled,Days,Start,DurationHours,MemoryGet-DedupJob | Format-Table Type,Volume,Progress,State

Give the optimisation job more memory and a longer window on a large volume.

PowerShell

Set-DedupSchedule -Name BackgroundOptimization -Memory 50 -DurationHours 9 -Priority Normal

Run garbage collection and scrubbing manually to reclaim space from deleted files.
PowerShell
```
Start-DedupJob -Volume E: -Type GarbageCollection -FullStart-DedupJob -Volume E: -Type Scrubbing
```
Deleting a file does not return its space immediately — the chunks remain until garbage collection runs. A volume that has had a large deletion will not show the space back until this completes.

Confirm it workedGet-DedupStatus shows a rising savings rate and the last job result is success.

PowerShell

Get-DedupStatus | Format-List Volume,SavingsRate,LastOptimizationResult,LastGarbageCollectionResult

If you need to undo itSet-DedupVolume can restore the previous settings. Start-DedupJob -Type Unoptimization reverses deduplication entirely, given enough free space.

Related faults

Where this stops. This write-up was written and checked by hand. It says what each step changes, how to confirm it worked and how to reverse it, and anything destructive is flagged before you reach it. If it does not match what your machine is doing, search the Support Centre for the exact code or message — and when something needs a person, get in touch.