[Zope] Re: Zeo as a Zeo Client

[Tres Seaver]

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David Pratt wrote:
> Andreas Jung wrote:
> 
>>
>> repozo does not help you syncing multiple ZEO server..it just performs
>> an incremental backup of an existing Data.fs file. And I don't know of
>> any solution have multiple "master" ZEO servers. There can be only one.
>>
>> -aj
> 
> 
> For sure. I guess the best one could have would be replicated storage
> clients that when offline could operate on their own data. When they go
> online they would first attempt resolve their data with the (master)
> server (synchronizing), and then append each new transaction to the
> local replica as it was occuring (replicating) so that before you went
> offline again, your storage is up to date.
> 
> I think this is all possible with a sync server, each client having an
> independent asynchronous loop for synchronizing, and a synchronization
> protocol for two way syncing. Zope has most of this now but it was never
> designed to provide data to the local storage to keep it up to date
> (while the zeo client is being used). This would be quite handy and I
> think there are some possibilities to do this.
> 
> I guess in a general way, this is what the spread is doing for ZRS but
> the mechanism and use case is different. I don't think you'd want any
> client to be offline for long with this service with a replicated
> storage client. I think the idea is more of a hot backup in case of
> failure of the main storage but I know little of ZRS.

ZRS secondaries go into "recovery mode" whenever they lose connection
with the promary:  that recovery is sufficient to allow it to resync
(even to bring up a new, "empty" secondary).


Tres.
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Tres Seaver          +1 202-558-7113          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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