[Bucardo-general] Regarding Bucardo's operation over unstable link

David Christensen david at endpoint.com
Thu Jun 18 03:32:25 UTC 2020

> On Jun 17, 2020, at 5:52 PM, Rodrigo Rodovalho <rodrigo.rodovalho at gmail.com> wrote:
> Hi,
> I was wondering if anyone could give some perspective about Bucardo's operation over a slow and unstable link between databases. 
> Just to provide some clarification and background: we would like to synchronize, in a master-to-master fashion, two databases. One of them would be a Linode instance running on a fixed IP. The other would be a home graded server in a small city, subject to a somewhat unstable connection, and also a *variable IP*.
> Is Bucardo ready to deal with the possible disconnection or IP changes? What would be the steps in order to keep the synchronization working with these environmental changes? In this case, I imagine that the best approach would be the Bucardo manager (and its database) being running in the machine with the variable IP, correct? Do you guys think that a VPN between the two machines is necessary?

Hi Rodrigo,

I agree with your idea to run the Bucardo daemon on the nose with the variable IP; even if you were using some sort of dynamic dns to keep things in sync this would minimize any downtime issues. 

I would assume (and perhaps this is a bad assumption) that the dynamic IP would in general or change while any connections were open, so only in a case of a server restart or similar might this be an issue. 

I don’t think a vpn would be required per se, but you would definitely want the Pg connections to be using SSL and would also need to ensure pg_hba.conf/server firewall is appropriately configured to minimize exposure to the general internet. Is there a way to detect from the static node when the IP for the dynamic node has changed?

> Also, the connection between the two points is rated at 5mbps. Is it enough, considering a very small use of 100 insertions/updates per hour of online forms (personal details, professional profile, etc)?

This seems completely reasonable and I would bit expect any substantial delays given what you describe. 



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