My secondary hard drive on my HP laptop is heating up and going offline.
When I restart the laptop it is back online.
Wondering if I should just replace the HD now?!
Is the HD on the way out?
I am not even using it, is this normal?
Its sure not normal. It does seem to me that the hard disk has serious trouble and is on its way out
Back up all the data on it ASAP
Hard drives can heat up quite a bit without taking damage, but going offline like that definitely is not normal, better back it up indeed.
Back up the hard drive contents and check that your ventilation and cooling systems are up to snuff. If this is an aftermarket hard drive you have added, you might consider using it in a USB enclosure instead to allow your laptop to cool.
Overheating hard drive means that it is also overheating the components around it because of the smaller form factor of laptops, so you can damage much more than your drive if you let it go too long.
I would definitely back it up to be safe, but it doesn't sound like the hard drive. Hard drives don't just "go offline" and then are ok.
Check ventilation to be safe. I would consider it more to be ventilation and fan failure before HDD failure.
How is your current laptop placed during operation? On a solid structure or an uneven surface eg. your lap, the bed, pillow etc. You could be facing a problem on overheating due to poor ventilation of your cooling area. As stated above your cooling fan could also built up with excessive dust and thus preventing proper air flow. Try having a look at that and if it's dirty, clean it with a small paint brush (try not to let the dust go back into the laptop during cleaning).
When you say going offline, do you mean the HDD icon disappers from the "My Computer" window? I've had the icon disapper from the My Computer window during operation of the HDD due to prolonged read/write error and comes back online after a complete shutdown. If that's the case, then your HDD is probably nearing its end.
Just scan your HD with a diagnostic program or something, just to make sure... if they come out all clean, I'd say get an external or buy another HD may i suggest RAID 10? Just remember every hard drive eventually dies.