Microsoft Deduplication reference: Starts a data deduplication job. The syntax and selected example below are adapted from the pinned Windows Server 2025 reference. Module availability, target configuration and delegated permissions determine whether it can run in your environment. Documentation and parameter text: Microsoft, CC BY 4.0; formatting adapted by Cmdlet World. No execution testing is claimed.
Use an account with the target resource permissions documented for Start-DedupJob. Modifying administrative cmdlets may require elevation or delegated administration. This catalog does not assert that ordinary users can execute the command.
Supported environments
Windows / Deduplication · Windows Server 2025 documentation; feature/module prerequisites apply
Parameters
-AsJob
Runs the cmdlet as a background job. Use this parameter to run commands that take a long time to complete. The cmdlet immediately returns an object that represents the job and then displays the command prompt. You can continue to work in the session while the job completes. To manage the job, use the *-Job cmdlets. To get the job results, use the Receive-Job cmdlet. For more information about Windows PowerShell background jobs, see about_Jobs.
-CimSession
Runs the cmdlet in a remote session or on a remote computer. Enter a computer name or a session object, such as the output of a New-CimSession or Get-CimSession cmdlet. The default is the current session on the local computer.
-Cores
Specifies the maximum percentage of physical cores that a job uses.
-Full
Indicates that garbage collection jobs free up all deleted or unreferenced data on the volume, if you specify the value GarbageCollection for the Type parameter. If you do not specify this parameter, garbage collection jobs free up space after a system threshold of delete data is exceeded. We recommend that you run garbage collection regularly without specifying this parameter, and then once a month specify this parameter and run garbage collection again. If you specify the value Scrubbing for the Type parameter, this parameter indicates that scrubbing jobs validate the integrity of all data on the volume. If you do not specify this parameter, the scrubbing job validates only critical metadata and data integrity issues that data deduplication previously encountered. We recommend that you run scrubbing regularly without specifying this parameter, and then once a month specify this parameter and run scrubbing again.
-InputOutputThrottle
Specifies the amount of input/output throttling applied to the deduplication job. Throttling ensures that deduplication does not interfere with other I/O intensive processes. The acceptable values for this parameter are: integers from 0 to 100. If you specify this parameter and the InputOutputThrottleLevel parameter, InputOutputThrottle takes precedence.
-InputOutputThrottleLevel
Specifies the amount of I/O throttling that the job provides to ensure that the job does not interfere with other I/O intensive processes. The acceptable values for this parameter are: - None - Low - Medium - High If you specify this parameter and the InputOutputThrottle parameter, InputOutputThrottle takes precedence.
-Memory
Specifies the maximum percentage of physical computer memory that the data deduplication job can use. For optimization jobs, we recommend that you set a range from 15 to 50, and a higher memory consumption for jobs that you schedule to run when you specify the StopWhenSystemBusy parameter. For garbage collection and scrubbing jobs, which you typically schedule to run in off hours, you can set a higher memory consumption, such as 50.
-Preempt
Indicates that the deduplication engine moves the job to the top of the job queue and cancels the current job. After the server cancels the current job, the deduplication engine cannot run the preempting job if the server does not have enough memory to run the job. This parameter applies to manual data deduplication jobs only and is ignored for scheduled jobs. You can preempt only deduplication jobs on multiple volumes.
-Priority
Sets the CPU and I/O priority for the optimization job run that you run by using this cmdlet. For jobs that you run when you specify the StopWhenSystemBusy parameter, we recommend that you set this parameter to Low. For typical optimization jobs, we recommend that you set this parameter to Normal.
-ReadOnly
Indicates that the scrubbing job process and report on corruptions that it finds but does not run any repair actions.
-StopWhenSystemBusy
Indicates that the server stops the job when the system is busy and retries later. We recommend that you specify this parameter when you set a low priority for the job.
-ThrottleLimit
Specifies the maximum number of concurrent operations that can be established to run the cmdlet. If this parameter is omitted or a value of 0 is entered, then Windows PowerShell® calculates an optimum throttle limit for the cmdlet based on the number of CIM cmdlets that are running on the computer. The throttle limit applies only to the current cmdlet, not to the session or to the computer.
-Timestamp
Specifies a date and time. This parameter applies only to unoptimization jobs. The deduplication engine unoptimizes only files that it optimized or reoptimized since the System.DateTime value that you specify.
-Type (required)
Specifies the type of data deduplication job. The acceptable values for this parameter are: - Optimization - GarbageCollection - Scrubbing - Unoptimization
-Wait
Indicates that the cmdlet waits for the job to complete and provides progress information to the client.
Prerequisites
Windows with the Deduplication module and the Windows feature or management tools that provide it. Confirm target connectivity and version compatibility using the linked Microsoft reference.
Security considerations
This cmdlet changes system state. Review every target and parameter in the official reference, test outside production, and prepare an appropriate backup or rollback. Do not execute the example automatically.
This command starts a deduplication optimization job on drive D: and consume up to a maximum of 50 percent of RAM. Source: Microsoft, CC BY 4.0; transcript prompt/output removed. This example was not executed.