The Windows Vista Disk Defragmenter has been improved over the Windows XP version, but you can’t see or use all the best features unless you run it from the command line. By default the defrag tool only defragments files smaller than 64 MB, because according to Microsoft’s benchmarks, fragments of this size, which already consist of at least 16000 contiguous clusters, have a negligible impact on performance. If you still want to defrag files larger than 64 MB too, you need to use the -w switch mentioned below to defragment files of all size.

Disk Defragmenter does not defragment files in the Recycle Bin, or files which are in use. Disk Defragmenter will not degragment Bootsect dos, Safeboot fs, Safeboot csv, Safeboot rsv, Hiberfil sys, Memory dmp, or the Windows page file. Using the -b parameter will optimize these boot files.

    Some swtiches that are available from the command line for Disk Defragmenter are:

    Specifies the drive letter or mount point path of the volume to
    be defragmented or analyzed.

    -c Defragments all volumes on this computer.
    Don’t specify a drive letter while using this.

    -a Performs fragmentation analysis only.

    -r Performs partial defragmentation (default). Attempts to
    consolidate only fragments smaller than 64 megabytes (MB).

    -w Performs full defragmentation. Attempts to