[nSLUG] Power Loss and UPSs

Jim Haliburton jim at on-site.ns.ca
Sun Nov 4 21:01:00 AST 2007


Hello all:
Well it is mostly over as I write this on Sunday evening.  This afternoon 
was delightful in Metro as those around here could see.  In my office the 
power came on between 1:00pm and 2.  Am not sure as I was out.

I am impressed that someone on the list has UPSs that will hold 50+ 
servers up for 2 hours.  That is a lot of battery power.

I am not so lucky.  On Friday I picked up 3 gallons of fresh high test 
gas for my backup generator.	Sometime after 5:00 this AM I realized the 
clock was not visible and as I bcame fully concious could hear the 
symphony of beeping coming from the server room which is almost under my 
bedroom.

Scrambled madly to find the flashlight.  Threw on some footwear and went 
and checked the status of all servers.  All were still up and running and 
could see the world.  Quickly fueled the generator and ran the power line 
to the server room.  Once the generator was started connected up, the 
wailing of the alarms stopped.

At this point I found the Novell server's UPS had run down as had my 
desktop system.  I just powered the UPSs off and left them.

Some post mortem points and items about the other responses.

1)  I should have fueled and test run the generator on Friday.
2) I should have run the extension cord to the server room Friday as 
well.
3)  Should have made sure I knew where the flashlights were last night.
4)  Really must track down the UPS control software for my all my 
servers.

You can apply these observations to your business case.

Test the UPSs before they are needed.  I know the Novell version of the 
software I had before would allow you to under software control switch 
over to battery power and monitor the life left as the voltage dropped.  
The app ran as an NLM on the server and a Windows app on a workstation 
talked to the NLM.

Plan ahead and decide which servers are needed to stay up and which can 
be powered down to extend the run-time of the UPSs.  I should have done 
this Saturday evening.

Can virtualization allow you to reduce the server count in times of power 
instability?

Can you move to a hot site easily if the power outage is accompanaied by 
infrastructure damage that will last longer term.  For example if the 
roof is blown off over your server room, where do you move to?

>From this I will refresh my planning.  Even as a small web hoster I have 
obligations to clients to keep running.  After Juan, my little generator 
ran 110+ hours without a break.  Once my ISP connection was re-
established we served our clients without shutdown.  And without power 
from NPSI.

It would be intersting to hear from others about their post mortem of the 
power outage.

Now most of my UPSs are back to 90+% fully charged.  Over the next few 
weeks I will test the run-time of each and start to replace ones whose 
run-time is less than what it should be.  With the low price of 
relatively good capacity, I have found it seldom useful to replace 
batteries.  The older UPSs are likely linear power supplies with large 
transformers etc.  New ones are far more efficient and give longer run 
times with the same amp hour capacity batteries.

One person mentioned putting car or truck batteries in their UPSs to 
extend their run time.  That may not be a good solution.  The batteries 
in most UPSs are designed with slightly different chemistry and a 
different charging plan than the batteries used in automotive use.  I 
have found when trying this, that the automotive batteries die in a short 
time from the charging that UPSs do.  In most cases less than a year of 
life.  It has all to do with the charging.  I was told that the UPS 
battery uses a "float" charge.  I do not know what the difference is 
between that and what a standard charger for automotive batteries does.

I look forward to hearing the experinces of others over this week-end.

Regards

Jim H

James A. Haliburton
On-Site Computer Services of Halifax
Suite 100, 25 Walton Drive
Halifax, Nova Scotia
Canada     B3N 1X6
Office/ Cell           : (902)499-5250
Home/After Hours : (902)477-8342
e-mail      : jim at on-site.ns.ca

Please avoid sending me MS Office attachments.   For an explanation see 
this:
http://www.nothingisreal.com/dfki/no-word




More information about the nSLUG mailing list