said by chinorider0:Possibly but it acts like the DVR is accessing the external HD on a random basis. Under 'normal' use of the external HD, there is virtually no sound but once or twice an hour, it sounds like the HD spins up for a few seconds and stops. I confirmed the spinning sound is the external HD
The DVR is continuously accessing the active hard drive. Whetrher you are watching, recording, or doing nothing. That is how it maintains a one hour buffer for each tuner.