You can schedule an Exchange data store for performing an unattended defragmentation pass. This makes the defragmentation more efficient with less impact on users. PerfectDisk's Schedule Wizard allows you to schedule the following types of schedules:
§ One Time Schedule - One Time schedules are used to perform defragmentation passes once. This option should be used if you want to execute a defragmentation pass once at some later time, such as in the middle of the night when data store load is lighter.
§ Weekly Schedule - Weekly schedules are used to perform defragmentation passes on a weekly basis. The interval between passes may be one or more weeks. This option should be used if you want to schedule regular defragmentation passes once a week or once every several weeks.