My computer usually stays switched on. Been like that since almost over a year I guess, with only a few shutdown/hibernate/restart here and there.
I have a database (Postgres) running on it to which at peak time have over 50-60 connections and almost all of them are reading and writing to it every ~2 seconds. On top of that I have shared a whole chunks of files too. I generally don't transact with huge file i.e. if they make it into my computer then they usually don't get deleted (just that I don't care to delete them, in case ...).
The computer is old, easily over 3-4 years old, and I've been using it for around one-and-half years. I'm guessing that the hdd is a minimum 2-2.5 years old.
Does shutting-down/hibernating reduce the life of an hdd?
Since I've oft noticed those who do so get failed drives in a pretty short spans. In fact, this guy, who once had a terrible hdd crash, told me that since I didn't switch-off my computer that's why my hdd was healthy and that he was following suit. The correlation seemed tight, but whether this correlation is because of a direct causation intrigues me.