We have a "static switch" in our datacenter that does what you are
talking about.  We plug single corded devices into it and the static
switch connects to 2 different UPSs so the single cord devices don't
lose power.
 
We had what Liebert is calling an "impossible reality" here over the
weekend:  one of our UPSs lost 6 batteries - one in each bank - and went
down hard.  It took too long to fail over to utility power and we had a
whole bunch of servers go down hard.  Since then we have been running on
generator power in parallel with commercial power so we still have our
full redundancy.  They say we are burning $7000 worth of diesel a day...
We are scheduled to switch back over to UPS power tonight.  Boy am I
glad it wasn't my turn to be on call.
 
-Brian

 

________________________________

From: [email protected] [mailto:[email protected]] 
Sent: Tuesday, June 16, 2009 12:05 PM
To: NT System Admin Issues
Subject: OT: Tripp-Lite PDUs



Greetings! 

I have a power supply situation that has me rather frightened... 

All our data and VoIP go through a single, non-redundant stack of Cisco
Catalyst 3750 network switches (which also supply power to the phones
via POE).  These switches have only a single power supply.  They are all
plugged into a single UPS.  Consequently, we have so many points of
failure I'm afraid to count them! 

Apparently Tripp-Lite has some PDUs (Power Distribution Units) that
feature "dual-input" with "Auto Transfer Switching" ("ATS").  They're
not cheap, but it _appears_ that ATS will allow one to plug the PDU into
two separate UPS units.  This way, if a UPS crapped-out royally and
would not allow even available line current to pass (we've had this
happen on some old UPS units), the company does not instantly blink out
of existance. 

Is this in fact what "ATS" with dual-input does? 

Any experience, etc as to how well these things work? 

Thanks! 

(Oh yeah, any other positive suggestions for dealing with this
situation?  I checked, and our particular Cisco switches do NOT allow a
second power supply to be added.  Top level stuff, huh?)
-- 
Richard D. McClary 
Systems Administrator, Information Technology Group 
  
ASPCA(r) 
1717 S. Philo Rd, Ste 36 
Urbana, IL  61802 
  
[email protected] 
  
P: 217-337-9761 
C: 217-417-1182 
F: 217-337-9761 
www.aspca.org <http://www.aspca.org/>  
  

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