[Beowulf] What is the right lubricant for computer rack sliding rails?

[Mark Hahn]

> The tricky thing with the "rack rail" approach (which we use a LOT at JPL)
> you give is that if the units have cases that are also full height, you
> can't stack one unit directly above another, so you have to leave a 1U gap.

OK, this may gross you all out, but why mount 1U's individually at all?
I'm a lazy slob, but I have several 1U's stacked on top of each other - 
after all, how often will you really need to get the non-top one(s) out?
depending on how fancy your servers are, saving the price of a rail kit
might even make $ense.  admittedly, I did this on an older cluster,
designed-for-cheapness cluster because I couldn't be bothered 
to order and assemble the rails...

wait, how about this: consider stacking 1U servers on their side.  you'll
still be able to pull them out if you want.  would the hardware care 
about the orientation?  muffin fans wouldn't, and disks out to be able 
to handle it.  come to think of it, there's no reason to think of this 
wrt conventional 19" racks.  you could just weld together a frame of nice
tough angle-iron supports (of whatever length you can manage to support 
the load without sagging embarassingly ;)

think of it this way: by omitting a proper rack and rails, you could probably
save something like $60/node.  can you think of a better way to spend $2400
(per rack)?  admittedly, that's probably only a few percent of total cost.