high availability issue of CAS

[Lin George]

Thanks Arthur!


From your below email, I take some time to learn the link you recommended. Looks like there are 3 solutions. All of them have pros and cons. In order to achieve high availability (when one server is down, the authentication system still works) and scalability (when the user base increases, we could add more servers in order to improve authentication performance) goal, which solution do you prefer? Or you prefer other solution?

CLUSTERING WITH REPLICATION
We have been struggling to get a clustering with replication environment setup using the JBoss Cache solution (JbossCacheTicketRegistry), which was outlined in the link you mentioned.  However, there have been some unexpected problems maintaining a stable JBoss Cache replication cluster.  Though it is maintained by JA-SIG, there aren’t many people you will find that are very experienced with it much less managing JBoss Cache; there are a number of people who will probably agree with me on that.  Another option for doing clustering with replication is to use the MemCacheTicketRegistry available in CAS 3.3.0.  This is the option favored by Rutgers, who is the primary maintainer of the CAS code base.  Scott B can testify about it being lightweight, however I don’t know anyone else that has deployed it in their environments.
CLUSTERING WITHOUT REPLICATION
If you want plain clustering without replication, then you could either go with a backend data store holding users SSO information and have the CAS servers be dummies by using the JpaTicketRegistry.  This would allow your users to hit any of the CAS servers and remove the need for replicating data, however you would have a single point of failure (data store).
FAIL OVER
However, most CAS deployments appear to use a active/passive fail over setup where you have two deployments and have your load balancer direct traffic to the primary and fail over to the secondary when necessary.  This option requires little / no major customization.


regards,
George

-----------------------------------------------------------------------------------------------------------------------------------
Message: 11
Date: Tue, 18 Nov 2008 14:27:00 +0100
From: Arthur Erd?s <ae at brainguide.com>
Subject: Re: high availability issue of CAS
To: Yale CAS mailing list <cas at tp.its.yale.edu>
Cc: cas-dev at tp.its.yale.edu
Message-ID: <1227014820.4087.34.camel at linux-1db0.techdivision.com>
Content-Type: text/plain; charset=utf-8

There has recently been a question concerning CAS load balance /
failover. Take a look at
http://www.nabble.com/Best-practice-for-CAS-load-balance-failover-td19912100.html - it might be what you are looking for...

Kind regards,
Arthur