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Date:      Thu, 16 Dec 1999 01:58:52 -0600 (CST)
From:      Kevin Day <toasty@dragondata.com>
To:        phk@critter.freebsd.dk (Poul-Henning Kamp)
Cc:        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:  <199912160758.BAA87332@celery.dragondata.com>
In-Reply-To: <14567.945330659@critter.freebsd.dk> from "Poul-Henning Kamp" at Dec 16, 1999 08:50:59 AM

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> 
> In message <199912160743.XAA49890@apollo.backplane.com>, Matthew Dillon writes:
> >
> >:>    NFS uses the kernel 'boottime' structure to generate its version id.
> >:>    Now normally you might believe that this structure, once set, will
> >:>    never change.  The authors of NFS certainly make that assumption!
> >:
> >:Is this another case of "lets assume the time of day is a random number" or
> >:is there any underlying assumption about time in this ?
> >:
> >:--
> >:Poul-Henning Kamp             FreeBSD coreteam member
> >:phk@FreeBSD.ORG               "Real hackers run -current on their laptop."
> >
> >    It basically needs to be a unique for each server reboot in order
> >    to allow clients to resynchronize.
> 
> Ok, then I suggest that you cache a copy of the boottime in the NFS
> code for this purpose.
> 

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? :)


Kevin


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