prevent operation on unmounted usb disk

[Marco Mandl]

Hello,

I use an usb disk for automated backup every night. The rest of the day
this disk is not used and unmounted.

Every few minutes ubuntu does something on this unmounted usb disk for
about ten seconds. I want to prevent this because it make a lot of noise.

Also I would like to stop this disk while it is not used. Is this
possible? How?

Regards,
Marco