Hi Adrian,
Generally it is best to have a minimum of 2 controllers with 2 backends per controller. If for instance, you have two controllers, and 1 backend per controller, and you were to loose 1 controller, you would need to take the other controllers backend db offline while you create an image (unless of course you have one that is recent) Even if you were to have an image, say by taking controllers 1 db offline to create it, at that moment in time while doing so, if you were to loose controller 2, you would loose connections from controllers to database as no database would be in a read / write state. In essence, trying to create a no single point of failure topology, that no one device creates an entire cluster failure, and as mentioned you must do a regular image of your db, depending on your circumstances this could be daily, weekly or even monthly depending on the size of your db and how long it takes to do a recovery. We for instance do one nightly, and purge the recovery log when we do so, of course the script that does so, must also make sanity checks that is not bringing the last db down in a cluster. Regards, > Hi all, > > We're trying to set up Sequoia and, with one controller with two > replicating backends, things work as described. We would like to have > some redundancy at the controller level as well, but we would like to > keep things simple (in the sense of not using more backends than > necessary), at the same time. Is it possible to have an additional > controller (to simply help out in the controlling function) for the > virtual DB without defining any backends for it? From reading the > docs, it seems that the controllers must have different backends, but > I take it that they must be defined. > > If the above is not possible, would it make sense to have one backend > per each (of two) controller? > > Thanks in advance for any enlightenment, > > Adrian _______________________________________________ Sequoia mailing list [email protected] https://forge.continuent.org/mailman/listinfo/sequoia
