Recommended Recommendation
How to set up deduplication in the most efficient way
The recommendation is to use Virtual Appliance instead of Windows Agent
It is not recommended to use disk defragmentation if you back up to the Acronis online storage and the disks are of considerable size.
If you run disk defragmentation after creating a disk/partition backup, the succeeding incremental backup will roughly be the size of the full backup. For detailed information please see Acronis Backup Software Creates Large Incremental or Differential Backup Archives.