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Power loss and system time when not having a battery backed RTC

Subject: Power loss and system time when not having a battery backed RTC
From: Attila Kinali <>
Date: Wed, 28 Mar 2007 16:39:14 +0200
Organization: NERV
Original-recipient: rfc822;

I have a little bit more general question than usual.
I have here a system that should be deployed in Joe
Average's house as a small appliance. While it is powered
it will gather information and store them on its flash.

Now, this system does not contain a battery backed RTC
(not enough space) and thus does not know what date/time
it is after boot. At a later time the device will
be able to get a time quote from a time server using
a wireless connection. But as the wireless connection
is triggered by a user action, it can happen hours after
boot. This means that there is a quite long period whithin
which the device does not know what time it is and hence
assumes it's 1970.

My problem lies now in the back jumps that the device
makes, when unplugged and replugged. On the filesystem
there will be files from 2007, while the system still
thinks it's 1970.

How do you handle this issue with the back jumps, if you
cannot stick in a batter backed RTC?

Thanks for your help

                        Attila Kinali
Praised are the Fountains of Shelieth, the silver harp of the waters,
But blest in my name forever this stream that stanched my thirst!
                         -- Deed of Morred

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