[mod_cluster-dev] [Fwd: mod-cluster and domains]

Paul Ferraro paul.ferraro at redhat.com
Fri Jul 17 12:54:07 EDT 2009

On Fri, 2009-07-17 at 16:51 +0200, Bela Ban wrote:
> Resent as the mod-cluster list didn't receive it
> -------- Original Message --------
> Subject: 	mod-cluster and domains
> Date: 	Fri, 17 Jul 2009 13:34:09 +0200
> From: 	Bela Ban <bban at redhat.com>
> To: 	mod cluster <mod_cluster-dev at lists.jboss.org>
> I've got a few questions regarding the functionality of mod-cluster:
> *#1 Does mod-cluster support domains with sticky sessions ?_
> _*I recall discussing this on *this* mailing list, and IIRC Paul 
> confirmed that mod-cluster supports domains with sticky sessions. I 
> actually tried this out and t worked.
> I just need a quick confirmation on this. For config details, I'll go 
> and re-read the archives.


> *#2 Disabling an entire domain*
> I want to disable not just 1 node in a domain, but all nodes in a given 
> domain. Is this possible ? If so, I'd assume this is done through 
> mod-cluster-manager ?

This is not yet possible.

> *#2a: How do I know when all sessions of all nodes of a given domain 
> have expired ?*
> This is necessary to know when I can shut down all nodes of a given domain

mod_manager reports the number of active sessions per node.  This logic
isn't completely accurate - as it defines an "active" session as one
that was accessed within the last 5 minutes.
To get accurate active session counts from each server in a domain,
you'll need to verify the activeSessions attribute of the individual
jboss.web:type=Manager,* mbeans via jmx-console, or similar.

The plan is to implement stop(...) management methods (i.e. for graceful
shutdown) that disables the node, waits for all sessions to drain, then
stops the node.
We'll allow this per domain as well.

> *#3 Starting an entire domain in disabled mode*
> I want to start all nodes, one by one, in a given domain as *disabled* 
> (all webapps). Is it sufficient to just start all nodes as disabled ? Is 
> it possible to start a node in disabled mode at all ?

This is not possible, atm.

> *#4 Enabling an entire domain*
> When all nodes in a domain have been started as disabled (step #3), I'd 
> like to tell the httpds to enable all (or a selected set of) webapps in 
> a given domain, in all nodes of that domain. Is this possible ?

In general, we have not yet implemented per-domain management functionality.
I'll create JIRAs for these.

> The point behind these 4 questions is that I want to demo how to disable 
> a domain, shut it down, upgrade the HW/SW, start it again, and re-enable it.
> -- 
> Bela Ban
> Lead JGroups / Clustering Team
> JBoss

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