Windows Defragmentation Decision Process

Windows Server 2012 Defrag does not just defragment Volumes like in earlier versions. There’s a decision process behind, that selects the appropriate method for each volume.

Decision Process

The following commands are based on the new Optimize-Volume PowerShell cmdlet. Most of the parameters correspond to defrag.exe’s parameters. The Decision process works like this.

# For HDD, Fixed VHD, Storage Space:
Optimize-Volume -Analyze -Defrag

# Tiered Storage Space
Optimize-Volume -TierOptimize

# SSD with TRIM support
Optimize-Volume -Retrim

# Storage Space (Thinly provisioned), SAN Virtual Disk (Thinly provisioned), Dynamic VHD, Differencing VHD
Optimize-Volume -Analyze -SlabConsolidate -Retrim

# SSD without TRIM support, Removable FAT, Unknown
No operation.

Graphical Defrag Tool

The classical GUI Tools for Defrag still extists. If you open it, you’ll see theres a predefined schedule for a weekly defragmentation of your system volume. Depending on the type of storage you’re using, defrag only will run a short trim or other optimization at that time. In virtualized environments, you have either thin provisioned storage from vSphere or from storage. Because of this, Defrag will not start a classical defragmentation anymore on VM’s. Instead, a re-Trim / Slab-consolidation will start and takes only a few seconds / minutes to complete (depends on size).

PowerShell cmdlet

Server 2012 R2 also has a PowerShell cmdlet called “Optimize-Volume” that can be used instead of the classic defrag.exe tool. Both can handle the same functions, the cmdlet has an additional StorageTier Optimization function for Storage Spaces.

Information about the cmdlet is here:
http://technet.microsoft.com/en-us/library/hh848675.aspx

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