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List:       zodb-dev
Subject:    Re: [ZODB-Dev] ZODB blob support.
From:       Toby Dickenson <tdickenson () devmail ! geminidataloggers ! co ! uk>
Date:       2005-03-21 18:08:35
Message-ID: 200503211808.35764.tdickenson () devmail ! geminidataloggers ! co ! uk
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On Monday 21 March 2005 17:50, Chris McDonough wrote:

> - People are are unwilling to accept any weakening of data integrity
>   guarantee and who want the ZEO server itself to be responsible
>   for writing data (the ZEO clients must send the server the data
>   over RPC).  OTOH, if configured properly, the data may be read
>   from a shared filesystem.

I suspect some weakening is inevitable, unless you severely restrict the 
choice of shared filesystem. Every network filesystem has its own ideas about 
when client caches should be flushed.

> I think we want to use something like what I'm told Toby does for
> DirectoryStorage (using os.rename in the 2nd phase, keeping a journal to
> be able to back out a failed 2nd-phase commit).

That works great on a local filesystem, but dont expect any strong atomicity 
or durability guarantees across networked filesystems.

-- 
Toby Dickenson
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