From: mgrmem@NeXTwork.Rose-Hulman.Edu (Mark Monnin) Subject: Re: how safe is minix filesystem in power failure? Date: 15 Apr 1993 18:02:08 GMT
In article <1993Apr14.145214.432@n5ial.mythical.com> jim@n5ial.mythical.com
(Jim Graham) writes:
> actually, the way UPSs normally work is more along the same lines as the
> battery in a telephone central office (switching center). basically, the
> entire phone system (including your telephone, provided it isn't one of
> the ones, such as cordless phones, that wants external AC power) runs off
> of the battery the whole time, whether external power is there or not.
> the external power, when it exists, is used to keep the battery charged.
> (in the case of the telco, there are *MASSIVE* generators to take over
> the charging of the battery when power failure is sustained.)
Be careful, your talking about on-line UPS. Many low
cost UPS's are off-line UPS (standby power supplies). BEST
uses a combination and "mixes" the power of both (to prevent
a failure in either the inverter or switch over from killing
your system).
Small UPS (esp. standby variants) are fairly cheap. About
US$150, I think. They won't stay up for long, nor will they
keep your monitor and printer going as well. But if all you
really need is to shutdown the system, 5 minutes is enough
time.
Locally, we have more problems with "power flickers" than
"power failures." Having a baby unit to keep the system
running over those times helps a lot.
-Mark Monnin
Mark.Monnin@Rose-Hulman.Edu