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Date:      Thu, 16 Dec 1999 12:14:54 -0600 (CST)
From:      Kevin Day <toasty@dragondata.com>
To:        nate@mt.sri.com
Cc:        phk@critter.freebsd.dk (Poul-Henning Kamp), toasty@dragondata.com (Kevin Day), dillon@apollo.backplane.com (Matthew Dillon), gallatin@cs.duke.edu (Andrew Gallatin), freebsd-current@FreeBSD.ORG
Subject:   Re: Serious server-side NFS problem
Message-ID:  <199912161814.MAA33594@celery.dragondata.com>
In-Reply-To: <199912161718.KAA19547@mt.sri.com> from "Nate Williams" at Dec 16, 1999 10:18:48 AM

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> 
> > In message <199912160758.BAA87332@celery.dragondata.com>, Kevin Day writes:
> > 
> > >Ack, I was using this very same thing for several devices in an isolated
> > >peer-to-peer network to decide who the 'master' was. (Whoever had been up
> > >longest knew more about the state of the network) Having this change could
> > >cause weirdness for me too... I assumed (without checking *thwap*) that
> > >boottime was a constant.
> > >
> > >Perhaps a 'real_boottime' or 'unadjusted_boottime' that gets copied after
> > >'boottime' gets initialized so that others can use it, not just NFS? :)
> > 
> > no, I think that is a bad idea.  In your case you want to use the
> > "uptime" which *is* a measure of how long the system has been
> > running.
> 
> Uptime is also a constantly changing number.  Forgive me for my
> ignorance, but why does bootime constantly change?  I would have thought
> it would be a constant?  I've got software that also uses this to
> determine when a new copy of it exists (although I do keep a local cache
> of the value in case my software crashes, since it can recover from a
> crash, but not a reboot).
> 
> I would think that boottime would be constant, since you didn't keep
> booting at a different time...
> 

Yeah, uptime is moving which makes it difficult for me too. When new
machines enter the network, they need to announce a number which is used to
decice who will become the master if the current master disappears. I could
just announce currenttime-uptime, but that's got a slightly different
meaning that I'll have to consider.

Anyway, enough of my proprietary mess, but... I do see a few uses for a
non-moving boottime, but won't argue here or now. :) This behaviour is
documented in time(9) though, so I really can't complain. :)

Kevin


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