Will CrashPlan completely fill a destination drive?
CrashPlan will not completely fill up a drive. CrashPlan stops backup to a drive if the minimum free space is 1% of the total drive size or 1 GB (whichever is smaller). After backup has stopped, CrashPlan runs archive maintenance in an attempt to free up space by removing deleted files, extra versions or files no longer selected for backup (based on your settings). Backup resumes once there is adequate space on the drive.