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). (See “3.5 Disabling journaling” on the second link).
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). (See “3.5 Disabling journaling” on the second link).