[CentOS] Emergency rescue help needed

[John R Pierce]

Anne Wilson wrote:
> Actually, I have one box attached to a BackUPS that is about 15 years old, and 
> has never had a replacement battery.  It holds the box through power 
> variations, and can supply power for a couple of minutes - enough to allow a 
> shutdown, since that box is never running unattended.  I got it when we 
> upgraded the company one - it was our (the company's) first, attached to the 
> file-server, so replaced at a reasonable age.
>   

all the BackUPs I've ever seen have been simple relay switched units.    
when the power is on,  you're getting unfiltered power (except for a MOV 
based surge protector), when the power is out, it switches to the 
"modified square wave" inverter output.   By comparision, the SmartUPS 
like my trusty old SU2000 at home, have boost/buck AC 'regulators' for 
brownouts and overvoltage, and relatively sinusoidal inverter output 
during total blackouts.    Since I put 4 x 20AH 12V batteries in this 
beast, I can run two PCs and my networking gear and LCDs for many hour 
long blackouts easily