If the objective is to have a second ZEO server available as a hot-backup, how about the idea of having ZEO clients with the ability to write to two separate ZEO servers (ideally running on separate hardware servers) with a single 'write' command? We can accomplish this at the application level, but it would be a nice option to have ZEO do it automatically. Is this a reasonable extension to ZEO? Jonathan ----- Original Message ----- From: "David Pratt" <fairwinds@eastlink.ca> To: "Andreas Jung" <lists@zopyx.com> Cc: "Tres Seaver" <tseaver@palladion.com>; <zope@zope.org> Sent: Tuesday, May 02, 2006 1:31 PM Subject: Re: [Zope] Re: Zeo as a Zeo Client
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.
Regards David _______________________________________________ Zope maillist - Zope@zope.org http://mail.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://mail.zope.org/mailman/listinfo/zope-announce http://mail.zope.org/mailman/listinfo/zope-dev )