From: Andy Hisgen (hisgen@caribe-85.eng)
Date: 03/11/97-11:34:57 AM Z
Date: Tue, 11 Mar 1997 11:34:57 -0600 (Central Standard Time) From: Andy Hisgen <hisgen@caribe-85.eng> Subject: Re: Time Synchronization Message-ID: <Roam4.0.5.858101697.28682.hisgen@caribe-85.eng> I'm rusty, but I'm not convinced that time synchronization is absolutely necessary even for embargo resolution. It should be sufficient (and necessary) to know that the difference in the clock rates between client and server, i.e., the difference in the rate at which their clocks advance, differs by a known upper bound. There should be no need for them to agree on what the actual absolute time is according to God (or the British Navy). In practice, that bound can be large, e.g., a factor of two. And it should be possible to design the protocol so that a client whose rate is wildly out of wack does not affect the correctness of the algorithm -- that client may not get any useful work done though. Caution: Even knowing that the clock rates differ by a known upper bound is problematic with very heterogenous clients. E.g., consider a notebook computer that goes to sleep. >Following on the discussion at Connecathon, upon checking the Spritely NFS >paper, I find that it does indeed require time synchronization between >client >and server, in particular for embargo resolution. > >It may be inevitable the if NFS V4 is going to include some enhanced cache >consistency abilities, it will require some form of time synchronization. >My >initial feeling is that this requirement may be incompatible with the desire >for >wide spread deployment of WebNFS clients, particularly on home PCs.
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