[lug] High Availability and Failover options

[D. Stimits]

I am curious if you already store the entire session state in some
format like custom programs or SQL, such that state is separate from the
program using it? If not, you would have to figure out something fairly
complicated, like snooping the core state of a running program and being
able to restart a new copy elsewhere; plus modify anything that is a
machine reference to the machine that originally owned the core. If
session state and data are already separated from the application
itself, you are a few miles ahead.

D. Stimits, stimits at idcomm.com

Andy Jolley wrote:
> 
> My company is looking for possibilities for a high availability java (JSP, API, BEANS) server and one of the options is Tomcat on Linux.  We currently have load balancers in front of another server solution that is frankly becoming too pricy and it's not living up to the salesmen's promises (big surprise).  So we're looking for a  new platform.  One of our main sticking points is ensuring the applciations have session level failover.  We currently have hardware level failover and load balancing via a hardware IP redirector.  While we're very happy with our hardware solution, we still have the issue of sessions being lost when a server goes belly up.
> 
> The development staff is working on coding to store the session information on an external data store, but I was wondering if there was a way to approach this a little more from the hardware/OS side.
> I was looking at Beowulf clusters, but what happens if one of the nodes in the cluster dies, and consequently what happens to the user sessions on that node.  I'm hoping the distributed memory model would help with this (unless the session was stored in the physical memory in the node that died).
> Redhat's website also mentions a product called Piranah, but I'm not too sure what that one is all about, it looks like basic load balancing.
> Does anyone have experience with any of this kind of thing..I'm starting to get pretty comfortable with Linux, but I can't even get Tomcat 3.3 running at home, so I'm obviously still pretty green with some of this stuff.
> 
> Thanks
> 
> Andy Jolley
> LAN/WAN Administrator
> jolley at firsttrust.com
> 303-294-5785
> 
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