[Seattle-SAGE] Server room build questions

Paul English tallpaul at speakeasy.org
Wed Apr 27 16:14:33 PDT 2005

I finally have a chance to set up a server room properly and I'd love to 
get some tips and feedback on what, how and who. 

We are looking at signing a 5 year lease and as part of the lease having 
the landlord build the server room space for us. I'm keen to be very 
specific about what we want to ensure that we don't end up getting stuck. 
We currently have 4.5 racks that we've built up over the last 3 years, and 
I think we will be adding 1 more rack in the next 6 months. We are looking 
at getting enough space for approx 20 racks which should be more than 

We have machines in 3 categories:  

3/4 rack of 24/7 critical customer-facing systems, network switches, T1 
CSU/DSU, etc. This probably won't be growing much.

1 rack of "operational" systems which can be down for 24 hours max. These 
are growing slowly to maybe 2 racks by the end of 5 years. 

All the rest which are growing the fastest are research style computational 
nodes which can be shut down for a day or two if necessary, and individual 
nodes can be up and down at various times with no issue. 

So on to the questions:
Given a commercial office space, does a roof-mounted AC make the most 

What are people's feelings on raised floors vs. tiles/anti-static carpet? 
I'm very opposed to running network/kvm cables under floors (give me a 
ladder rack any day), but raised floors can be handy for routing AC to the 
front of the racks and running fat trip-causing power cables. 

How much AC should I spec - get the maximum capacity 20 rack's worth now, 
or get a lesser amount now and plan to upgrade? 

Should I spec out a backup AC? Or just plan on shutting down all of the 
non-critical systems in the event of an AC failure. 

How much power should I spec? On this one I'm fairly sure that I should 
probably spec the full 20 rack's worth (200A?) and just get the breaker 
panel put into the room with circuits sufficient for 6 racks. 

What are the considerations for a backup generator vs large (Liebert?) 
UPS? I'm leaning towards an auto-start generator right now, with small 
rack-mount UPSen on the 24/7 critical systems. 

Do we bother with a fancy dry fire supression system? Seems like a major 
PITA and would take a big chunk out of the budget for everything else. 

Thanks in advance for the feedback. I think the answers will be useful 
to everyone but if you feel like sending me your answer off-list I will 
summarize the replies.


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