From: Peter Staubach <staubach@redhat.com>
Subject: Re: Data coherency trouble with multiple clients on2.6.14-rc5
Date: Mon, 07 Nov 2005 11:52:04 -0500
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Cc: Trond Myklebust <trond.myklebust@fys.uio.no>,
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To: "Lever, Charles" <Charles.Lever@netapp.com>
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Lever, Charles wrote:

>>On Mon, 2005-11-07 at 08:08 -0800, Lever, Charles wrote:
>>
>>    
>>
>>>in the case of "noac", OTW writes are always synchronous.  thus you
>>>should never have the problem where concurrent async writes 
>>>      
>>>
>>will obscure
>>    
>>
>>>server-side changes on "noac" mounts.
>>>      
>>>
>>However reads are not synchronous, nor are they ordered. You have no
>>guarantee that the RPC READ call that filled the first page 
>>you read was
>>handled by the server before the read that filled the next page.
>>    
>>
>
>yes, but the client can make use of WCC in the case where it's own
>updates are always synchronous, right?
>

As long as the writes are synchronous with respect to the system call 
and there
is no sharing going on, ie. two processes reading or writing at the same 
time.

    Thanx...

       ps


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