Optimizing your internal hard disk drive (40GB) (for PlayStation®2) (HDD) can create additional free space on the HDD. Optimize your HDD only if you've received a message that there isn't enough space to install software or data on the HDD. Optimizing the HDD is most effective if done after software or data has been deleted from the HDD.
NOTE: This operation may take a long time to complete depending on the volume and location of data stored on your HDD. Once optimization is underway, do not turn off your PlayStation®2, open the disc tray, or remove the HDD from your PlayStation®2.