The increase in used space on your database drive can be caused by the following:
If alot of rejected calls have been reprocessed, it is possible for the drive to jump in size.
Rejected calls
Unswept ZLB's. (Check that the sweeper is running.)
Screenshots and screenshots without recoridngs will also take up space.
If an increase in call volume has been experienced prior to the archive\purge date can also increase the database