[Zope] Re: Zeo as a Zeo Client

[Paul Winkler]

On Tue, May 02, 2006 at 10:23:40AM -0400, Tres Seaver wrote:
> I would look for a replication strategy to create your "intermediate"
> storage server:  the setup you are trying is not supported by the
> current ZEO setup.  Such strategies include:
> 
>   - Zope Corp's "Zope Replication Services" product, which keeps the
>     "secondary" storage servers synchronized with the primary via
>     the "spread" toolkit.
> 
>   - DirectoryStorage can be used to do replication via rsync.

... but you can't use a DirectoryStorage replica as a "hot" or "warm" backup.

DirectoryStorage replicas are pulled from the master storage, and no
storage process can be using the replica storage while this pull is
happening - not even in read-only mode. This is documented at
http://dirstorage.sourceforge.net/replica.html

For more background discussion, see these threads - 
why hot failover won't work:
http://sourceforge.net/mailarchive/forum.php?thread_id=4906719&forum_id=9987
some talk about cold failover:
http://sourceforge.net/mailarchive/forum.php?thread_id=7828511&forum_id=9987

-- 

Paul Winkler
http://www.slinkp.com