Seagate External Hard Drive User Manual
difficult question of external drive?
I just got a Seagate FreeAgent external hard drive with 500 GB of space on it. How do I ensure that the stuff I put on it (pictures, videos, etc.) are not deleted forever? Does disconnecting the computer or taking make me lose something? The manual does not say much more. Also, how long should I let him act / when do I disconnect? Thank you! 
You must unplug the external hard drive from the PC using the "Remove Hardware" icon in the systray, assuming that is connected via USB. It is still the use of a large Flash Drive (USB Thumb Drive). You can leave it on for as long as you want and disconnect whenever you want by using the method described above. Do not remove power from the external drive before disconnecting the PC (USB cable).