SQL database server data drives typically contain large to very large files (databases, indexes, workspace, temporary files) that may or may not become highly fragmented. If such files become heavily fragmented, perform a SMARTPlacement or Consolidate free space to defragment files and consolidate free space on affected drives.
While SQL does NOT need to be stopped to defragment these files, if a SQL Server is heavily used, you may want to consider defragmenting during non-peak hours so as to minimize the impact on disk activity. You may also want to configure PerfectDisk to run at a low CPU priority and/or to monitor and throttle Disk I/O usage. On an ongoing basis, the drive should be defragmented if a database device becomes heavily fragmented (500+ fragments). For the OS drive, perform an initial SMARTPlacement defrag pass to defragment files, optimize their on-disk placement, and consolidate free space. On an ongoing basis, defragment the OS drive using SMARTPlacement at least monthly. For best defragmentation speed, and improved performance on SQL database server drives, do not use Aggressive Free Space consolidation on OS or SQL server database drives.