Is there any particular reason why an Active/Passive redundancy model was used, rather than having two simultaneously active web servers, and two database servers with Master-Master replication? It would be much more practical to have a setup like this behind a load-balancer, so that manual intervention is not required if/when an outage occurs.
Is there for instance a Green/Blue deployment of Bahmni, which can also allow for fail over and upgrades without downtime?
Thanks for re-locating my question, Gurpreet - it’s greatly appreciated.
Green/Blue deployment isn’t quite what I’m looking for, however, as I would like to have both server ‘pairs’ (i.e. both database servers and both web servers) active at the same time. I can handle sticky sessions (if necessary) through my load balancer (i.e. HAProxy), and I’d imagine Master-Master replication should be okay, given UUIDs are used for Primary keys, rather than auto-incremented integers - if need be, however, I could always add an auto-increment offset to one of the servers.
Anyway, here’s a rough overview of what I’m aiming to achieve. Please forgive the rushed quality of the diagram.
Hi @andrewwalter,
In the master-master setup, the failover is automatic without any manual intervention. The following are some points to consider. Please note that these are just my views.
The implementations that we work on are low-resource setting in terms of hardware configuration. The production master databases are of high configuration but the slave configurations are not on-par. Given that the master-master setup needs a lot of hardware - databases, web and load balancers - it can become too much to manage.
We generally go for master/slave setups and the time lag of switching a master to slave manually in case of failure is considered reasonable in our setups.
The other consideration in master/master slave could be that of consistency. The writes can happen in any of the databases and there can be a inconsistent behavior if the reads happen from alternate database (for small duration though).
Also, given this setup, it can be difficult to configure unless you have an automated and repeatable way of setting it up.
