defrag Volume

defrag Volume [/a]

defrag Volume [/a] [/v]

defrag Volume [/v]

defrag Volume [/f]

Volume

The drive letter or a mount point of the volume to be defragmented.

/a

Analyzes the volume, displays a summary of the analysis report, and indicates whether you should defragment the volume.

/v

Displays the complete analysis and defragmentation reports. When used in combination with /a, displays only the analysis report. When used alone, displays both the analysis and defragmentation reports.

/f

Forces defragmentation of the volume when free space is low.

/?

Displays help at the command prompt.

• A volume must have at least 15% free space for defrag to completely and adequately defragment it. Defrag uses this space as a sorting area for file fragments. If a volume has less than 15% free space, defrag will only partially defragment it. To increase the free space on a volume, delete unneeded files or move them to another disk.
  
  
• You cannot defragment volumes that the file system has marked as dirty, which indicates possible corruption. You must run chkdsk on a dirty volume before you can defragment it. You can determine if a volume is dirty by using the fsutil dirty query command. For more information about chkdsk and fsutil dirty, see Related Topics.
  
  
• While defrag is analyzing and defragmenting a volume, it displays a blinking cursor. When defrag is finished analyzing and defragmenting the volume, it displays the analysis report, the defragmentation report, or both reports, and then exits to the command prompt.
  
  
• By default, defrag displays a summary of both the analysis and defragmentation reports if you do not specify the /a or /v parameters.
  
  
• You can send the reports to a text file by typing >FileName.txt, where FileName.txt is a file name you specify. For example:
  
  defragVolume/v>FileName.txt
  
  
• To interrupt the defragmentation process, at the command line, press CTRL+C.
  
  
• Running the defrag command and Disk Defragmenter are mutually exclusive. If you are using Disk Defragmenter to defragment a volume and you run the defrag command at a command-line, the defrag command fails. Conversely, if you run the defrag command and open Disk Defragmenter, the defragmentation options in Disk Defragmenter are unavailable.
  
  

To analyze drive C, type:

defrag C: /a

To analyze drive C and display the analysis report, type:

defrag C: /a /v

To defragment drive C, type:

defrag C:

To defragment drive C and display the defragmentation report, type:

defrag C: /v