To do the tune-ups, the usb drive must be unmounted. But it might not be as relevant as I thought… the same wiki entry says, that if you do 10gb of write operations per day, the USB drive (whitout tune-ups) should last you 10 years. But you still might consider disable journaling as it will speed things up (less of those costly write operations).
I should’ve been more specific, the content is hidden deeper in the wiki, you have to follow the links:
To do the tune-ups, the usb drive must be unmounted. But it might not be as relevant as I thought… the same wiki entry says, that if you do 10gb of write operations per day, the USB drive (whitout tune-ups) should last you 10 years. But you still might consider disable journaling as it will speed things up (less of those costly write operations).