why does it say "warning" under my disk health?
- Because the values of SMART attributes (plural) of your HD have reached such a dangerous level that the data stored on your HD are running the risk of getting lost. Your HD is (in the 1st stages of) failing.
and...
your drive may last 1 more week, or another year.
so your backups (you know, the ones you do regularly, right ) become even more critical knowing your drive may fail sooner rather than later.
but even without the fore-warning of your SMART values (which personally I take with a grain of salt), drives die at the drop of a hat.