Shut down or leave on?

["Richard Carter" <carter.r.a.l@gmail.com>]

Hi Folks,

Is it better to leave a system running all the time or is it better to shut it down over night, on weekends, holidays etc?  

In the past I have always shut my Debian system down over night etc for 3 reasons: 

1) I put backups on my 80GB external HD which I usually leave shut down even when I boot the rest of the system.  It's about the same age as my internal 160GB HD so I hoped to reduce the probability of it failing at the same time as the internal HD by starting it less often.  

2) I hoped to reduce the probability of being hacked by shutting down, although I do have a firewall installed.  

3) I thought it was a waste of electricity, and money, to have a machine running that wasn't being used.  

But I notice that most backup utilities are designed to backup automatically at the same time every day or week.  That seems to assume that the system is always running. 

I'd appreciate your advice.

Robin Carter