It would look for media that is overwritable/appendable in the media set assigned to the running job, and failing that it would look for Scratch media.
EDIT: This is how it would work with an unpartitioned autoloader/library. Should you have partitions, you need to ensure your tapes are available to be appended too or overwritten. If not, the job would either fail or queue.
Depends on 3 things...
- whats set under tools - options - media management
- whats set under the backup job properties
- lastly upon the media set & the tapes present...
and again, it multiple media (tapes) meet a certain requirement, then any random media would be used for the backup...
...if your tapes in your media set aren't overwritable or appendable, or aren't present in the autoloader/library/tape drive then BE will pick another tape that is if it is in the Scratch set.
my ststus is that all tapes is overwritable and configured with media sets , 5 of them in media set called daily to tape , and one in a weekly to tape media set, however i might choose the weekly configured tape to write on in a week day .