On Fri, Jan 20, 2012 at 9:21 AM, Marvin Addison <[email protected]> wrote: >> This is caused by the service ticket being written to one node of the MySQL >> cluster, >> but then the other CAS node happens to get to do the service ticket >> validation, >> and it happens to use the other DB node, the ticket isn't found, because >> database >> replication hasn't been fast enough to bring the ticket over. > > I assume you're using traditional master-slave replication where no > amount of tweaks will _guarantee_ replication on a timescale that > would work in all cases. I believe you MUST use multi-master MySQL > replication in order to make this work properly. Bill Thompson > mentioned recently that he'd worked on such a setup and it worked > admirably, so perhaps he can weigh in here with more information. >
The HA CAS setup we helped build for Lamar University is a multi-node multi-site active/active architecture. The ticket registry is a multi-master MySQL with synchronous replication. The solution actually included two CAS clusters...one in each data center with some fancy routing to make sure validate request ultimately land in the right cluster. This solution is working well for Lamar. They happened to be in hurricane alley and frequently use the alternate data center. The decision to go with JPA and MySQL was mostly due to Lamar's experience and expertise with MySQL. We've also helped University of New England (Australia) with a similar HA CAS setup, but based on Ehcache (w/ simple RMI replication, not Terracotta). They have been running in production since January 2011 and report that their 2 node Ehcache setup has been running "flawlessly". I'd recommend seriously considering your HA requirements and the possibility of running a single node deployment, especially if you running on virtualized hardware with inherent redundancy and scalability. If you are convinced you need multi-node deployment, I'd try out Ehcache. Happy to go into further details with you. I should also point out that Unicon of course provides consulting and support for CAS deployments if you're looking for more direct help. Best, Bill -- You are currently subscribed to [email protected] as: [email protected] To unsubscribe, change settings or access archives, see http://www.ja-sig.org/wiki/display/JSG/cas-user
