Before using Partition Assistant we highly recommend you do a complete defragment on the partition which you want to resize. The built-in defragment tool could assist you achieve this goal. Here are two methods of "How to defragment partition in Windows OS".

  1. Open My Computer.
  2. Right-click the local disk volume that you want to defragment, and then click Properties.
  3. On the Tools tab, click Defragment Now.
  4. Click Defragment.

  1. Start Computer Management MMC (Compmgmt.msc).
  2. Click Disk Defragmenter.
  3. Click the volume that you want to defragment, and then click Defragment.