[Beowulf] Green Cluster?

[Brian Oborn]

[snip]
> Generally speaking, if you have a large cluster, and you have enough
> work for it, it is going to be running flat out 24x7. If it isn't,
> you've bought more hardware than you need.
>   
There are many cases where a cluster is not used for continuously for 
calculations, but rather to reduce turn-around. Our cluster for instance 
is sitting idle at least 1/2 the time, but keeping it's size to the 
point where when people do run they can get their results back in 8 
hours or less makes them much more productive. This way they can look at 
the results, tweak things as necessary, and run again while the setup is 
still fresh in their mind.
> Again, though, I think you might want to ask if you're doing the right
> thing here. If all your machines are not working flat out 100% of the
> time, you have hardware depreciating (and rapidly becoming obsolete)
> to no purpose, and there are loads of people out there, probably even
> on your own campus, who probably are desperate for compute
> cycles. (Hell, I could use extra cycles -- I can never afford enough.)
>   
We've been trying to encourage other departments on campus to use some 
of our extra cluster time, but with rather mixed results.
> Optimally, a cluster will be working 100% of the time, until one day
> when it is obsolete (that is, the cost in space, power, and cooling
> is more than replacing it with faster/better hardware), it gets shut
> down, replaced, and sold off.
>
> Perry
>