External drive keeps turning on and off while in standby

You want standby

Turn off storage means whether it should turn off any drives you have connected via USB

If you have an external drive connected then you will hear it vibrate through the desk. Or it could be the internal hard drive working away while its on standby. Try changing the power mode and see if it still happens.

Does the external hard drive ever turn off when the Xbox is off?

The console has a setting to turn external storage off when the console is turned off. It's in the power settings. However, for some reason, some externals do not turn off when the console is turned off, even when the "When Xbox is off, turn off storage" setting is enabled.

The second thing that will cause most externals to go to sleep is inactivity. Usually there is a setting in the drive's own firmware that says "go to sleep after 30 minutes of inactivity" or whatever.

Here's what I would recommend: -

1. If it's not already enabled, enable the "When Xbox is off, turn off storage" setting in the console's power settings, then test to see if the drive turns off when the Xbox is turned off.

2. If option 1 is no help and the drive never turns off, disable that setting, then see if the external turns off after a period of inactivity once the Xbox has been turned off.

If you unplug the drive when the console is off, obviously, if you have the console set to automatically update your games/apps, it won't be able to update anything on the external while the Xbox is off as it's not connected. That is the primary downside of what you're currently doing.

If you are storing your games on an external drive make sure the power to the drive is not turned off while in instant on mode.

Hope this helps. Good Luck.

I turned off the Xbox overnight and not had the problem since. Is there any known complication keeping it not turned off completely (standby) all the time?