Keep in mind the Following Points before performing Disk Defragmenter

Perform Analyze before defragmenting a volume

• Analyze volumes before defragmenting them.
• It tells you the percentage of fragmented files and folders on the volume
• Recommends whether to defragment the volume or not .

Analyze after adding large numbers of files

It is best practice to analyze Volumes because it becomes excessively fragmented when users add a large number of files or folders.

Ensure the volume has at least 15% free space

• To perform defragmention in complete and adequate manner a volume must have at least 15% free space .
• Uses this space as a sorting area for file fragments.
• If a volume has less than 15% free space, Disk Defragmenter will only partially defragment it.

Defragment during low-usage periods

• Defragment file server volumes during low-volume usage periods to minimize the effect that the defragmentation process has on file server performance.
• The time that Disk Defragmenter takes to defragment a volume depends on several factors, like

1. The size of the volume
2. The number of files on the volume
3. The number of fragmented files
4. Available system resources.

After installing software or installing Windows

Defragment volumes after installing software or after performing an upgrade or clean install of Windows.