Orvell Monitoring requires 15 - 40 MB of disk space per day for recordings, depending upon user settings, such as how frequently you save screen snapshots, whether you save in full colour or grayscale, how many days of recordings you save, and how many hours a day the computer is used and how many days you allow the software to record before automatically deleting recordings. They recommend 0.5 GB of available hard disk space, which would be enough for more than one week of recordings with the default settings.