The lifespan for a hard drive is just 4 years, assuming ''average'' use. The simple spinning, reading, and writing is what leads to its demise, so the cause of death, according to the corroner's future autopsy, will be having lived a long and fruitful life serving its purpose.
Unfortunately there's no way of telling how much longer it has to live as current medical technology is only capable of determining the imminent failure. Although you would like your friend to last as long as possible, perhaps it's best for a quick death, as every moment of life is aggony for the failing drive. I'd suggest performing an immediate operation, extracting every bit of knowledge from your friend's brain, then letting it advance to technology heaven (AKA the junkyard).
While there is/was no way of preventing this occurance, the weekly/monthly (depending on your usage) defragmentation of your friend's brain can help prevent undue strain on its memory. Not only can this method of physical therapy help delay the inevitable, but it can also help prevent Alzheimers, which is what causes a delay remembering where a certain file is located, and then accessing it.
And, as always, remember to have your drives spayed or neutered. 
Hope this helps,
John
Can anybody tell me what CAUSED my hard drive to go bad? Why it's crashing?
I kept checking with antivirus and it said I had none?
I probably won't get to see the answer to this question but I was just very curious WHAT CAUSED my problem?
Thanks
Sue
Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic