So, it looks like our changes on Wednesday actually solved the session relate problem. The rate dropped way off and after investigating some more there was a more normal way the error could occur also.

Adding the "always-save" and "always-load" parameters seemed to fix the problem in general.

I would not assume that updates the cluster were synchronous as this could delay serving pages. However, I would assume that there are safe guards in place to prevent outdated data from replacing more recent session changes assuming all servers remain online?

In any case, our cluster is behaving as expected again.


Scott Ferguson wrote:

On Mar 13, 2008, at 12:24 PM, Andrew Fritz wrote:

Just did about 30 refreshes and it always comes back web1, never web2. (request URL is entirely different, in a different domain in face; it is returning the expected fully qualified local host name).

I'm not sure what brand/model the load balancer is. I'll put a call into our hosting service to verify that. I have confirmed with them that sticky sessions are enabled on the load balancer and the above test seems to confirm that.

Shouldn't using the cluster session store result in bouncing from one server to the other NOT being an issue? Isn't the whole point of clustered session to ensure that no matter which server serves the request, the session is available correctly? Or have I missed something?

Yes, but sessions aren't transactional.  So there's a window where an update on one server might not be seen by a second server.  The save-mode of the session-config gives you some more control over when data gets sent to the backups.

-- Scott


Andrew Fritz wrote:
We are actually doing basically that on every page of the site. I put 
the local host name in the footer. That is how I've confirmed. I'll try 

Let me get the model number on the load balancer and reply with that also.


Serge Knystautas wrote:
Both the add and remove behavior you're describing is exactly what would 
happen if the load balancing was not sticky across 2 servers.  What kind 
of load balancer are you using?

I would try to confirm by creating a JSP like this:


and hit it repeatedly to confirm that stickiness is working.  I don't 
know the PHP syntax offhand to do the same, but just something to print 
the IP address of the server you hit.


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