-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
János,
On 4/13/2011 1:01 PM, János Löbb wrote:
> My problems are starting with the requirement of removing a server from the
> cluster and adding it back to the cluster without affecting the users. I
> know just three ways to take a server out from the cluster. I assume
> "server" here means a tomcat instance.
> - shut that tomcat down.
> - comment out the <Cluster..../> tag and let tomcat re-read the config
> change, although I do not know how to do that. I do not see any "graceful"
> options.
> - Change its multicast address and again re-read the config change
> somehow.
> Is there any command line or web based interface that can interact with the
> running cluster and take a cluster member "out" and put it back later ?
mod_jk has a life configuration screen ("jk status manager") that allows
you to remove a member from the load-balancing portion of the cluster...
that Tomcat will still communicate with the rest of the cluster for
session distribution, though, and that might not work well in your
environment: potentially lots of de-serialization issues.
> If I just shut down the web application on one cluster member it
> renders all the replicated sessions of the webapp on other tomcat
> unreachable via the reverse proxy, I already tested that out.
Really? I would be surprised if, in a distributed-session environment,
the removal of a server expired all the sessions it initially created
across the entire cluster. That would not be useful under any
circumstances. Maybe I don't understand what you're trying to describe.
I think you want to do something like this:
1. Disable the target server via jk-manager: this stops traffic from
being sent to it. Now, you can safely stop the target server without
interrupting any real users.
2. Stop the target server, remove the <Cluster> configuration,
upgrade your webapp and re-start the server.
3. Direct your users to use a special URL that takes you directly
to the target server and does /not/ use the jk-managed cluster.
When you're ready to re-join the cluster:
4. Stop the target server, re-enabled the <Cluster> configuration,
re-deploy the same version of the webapp that is available
on the other cluster members, and start the server.
5. Re-enable the target server via jk-manager
Everything else you said seems to be way-over-thinking things.
- -chris
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.10 (MingW32)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
iEYEARECAAYFAk2mClEACgkQ9CaO5/Lv0PAq9gCcDzK6VkJfO8gcQKu5BAs0+CX4
EhAAoLm6cTrkLUF5zrXLSUJvnj0l34dj
=WsOP
-----END PGP SIGNATURE-----
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
