I finally found this document NOT referenced from the main README file in the repmgr repo. https://github.com/2ndQuadrant/repmgr/blob/master/docs/repmgrd-node-fencing.md I guess the default solution is pgbouncer Any simpler solutions for this tricky problem? Regards, Aleksander On Mon, Aug 14, 2017 at 5:03 PM, Aleksander Kamenik <aleksander.kamenik@xxxxxxxxx> wrote: > Hi! > > In a cluster set up with postgres 9.6, streaming replication and > repmgr I'm struggling to find a good/simple solution for avoiding > split brain. > > The current theoretical setup consists of 4 nodes across two data > centers. The master node is setup with 1 of 3 synchronous replication. > That is it waits for at least one other node to COMMIT as well. > repmgrd is installed on every node. > > The clients will use postgresql JDBC with targetServerType=master so > they connect only to the master server in a list of four hosts. > > The split brain scenario I forsee is when the master node locks up or > is isolated for a while and comes back online after repmgrd on other > nodes have elected a new master. > > As the original master node has a requirement of one synced > replication node and the remaining two standbys are streaming from the > new master it will fortunately not start writing a separate timeline, > but will still serve dated read only queries. For writes it will > accept connections which hang. The repmgrd instance on the original > master sees no problem either so does nothing. > > Ideally though this instance should be shut down as it has no slaves > attached and the status on other nodes indicates this master node is > failed. > > Any suggestions? I'm trying to keep the setup simple without a central > pgbouncer/pgpool. Any simple way to avoid a central connection point > or custom monitoring script that looks for exactly this issue? > > Also, do you see any other potential pitfalls in this setup? > > Thanks for thinking this through, > > Aleksander > > -- > Aleksander Kamenik -- Aleksander Kamenik -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
