On 9/7/07, Orion Letizi <[EMAIL PROTECTED]> wrote:
>
>
> Vis a vis IP addresses, the command 'ec2-describe-instances ' will show
> you
> the hostnames of the instances you have running.
>
> The terracotta server doesn't need to know the IP address of a connecting
> JVM.  Each JVM that connects to the terracotta server needs to know the IP
> address of the server, but not the other way around.


But you dont know the IP address of the terracotta server until you launch
the EC2 instance. So you need a way to, on the fly, tell all the servers
what the master server's IP address is. I know it can be done, but the devil
is in the details. The fact is I havent heard of anyone who *has* done it,
or who has published code or an AMI.


When I've set up
> terracotta clusters on EC2, I assume that the server is long lived.  I
> haven't really thought about how to make an entire cluster just start up
> without some configuration, but I'm sure there's some clever way to do it.
>


This is critical since in a real environment you *cant* assume that the
server is long lived - particularly on EC2 where you loose everything - your
IP address, machine name, and data.

Vis a vis what happens if the terracotta server goes down: you can run them
> in pairs (or, really, any number) so that if the primary server goes down,
> a
> secondary will automatically take over.  The servers can be synchronized
> using a shared disk (e.g., NFS) or over a network.


There is no shared disk in EC2. There is S3, but  it is not NFS and not
random access. It really is only useful right now for backup, not as a
shared disk between two servers.

Running tomcat clustered with terracotta on EC2 is really no different than
> running tomcat clustered on any other multi-node environment.



I would beg to differ, because not having stable IP and Hard disk is a big
difference.

  What
> information, specifically, are you looking for?


What I am trying to figure out  is how to use tomcat on EC2 in a safely
deployable way. Terracotta seems like a good way, though it appears a real
deployable scenario isnt quite worked out. By your question it sounds like
you may not realize that this is the *** #1 *** issue in the EC2 community.
There are no good solutions - at least that have been published - for
cleanly dealing with no static IP address, no persistent disk, and the
related issues of load balancing, scaling and restarting.

For you guys (terracotta), getting a clean simple setup for running
terracotta + tomcat on EC2 would be a *huge* win for establishing it in the
EC2 community since it is such a critical issue.

Regards,
Hank
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