From: Peter Staubach <staubach@redhat.com>
Subject: Re: Data coherency trouble with multiple clients,	on2.6.14-rc5
Date: Wed, 26 Oct 2005 14:45:35 -0400
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Cc: "Lever, Charles" <Charles.Lever@netapp.com>,
	Charles Duffy <ccd@mailcall.com.au>, nfs@lists.sourceforge.net
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To: Trond Myklebust <trond.myklebust@fys.uio.no>
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Trond Myklebust wrote:

>on den 26.10.2005 klokka 08:27 (-0700) skreiv Lever, Charles:
>
>  
>
>>i agree that O_DIRECT is the right solution.  however, even with "noac"
>>i would expect mr. duffy's workload to behave correctly most of the
>>time.  sounds like he is able to make it fail very easily.
>>    
>>
>
>Why would you expect that?
>
>"noac" does not turn off data caching, nor does it change the policy
>that the client will not invalidate the data cache while it is holding
>the file open for write.
>

It seems to me that the policy should be to allow cache 
validation/invalidation
unless the file is mmap'd for writing or if there are active WRITEs 
outstanding.
Simply having the file open for write should not affect the consistency 
model.

    Thanx...

       ps


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