To follow-up on the previous post about Sametime install, I went back thru my notes.
We set up a WebSphere cluster with 2 ST Proxy servers in Europe and 2 ST Proxy servers in Asia Pacific. The ST Console was installed in Europe. We wanted to manage servers from one single ST Console.
When we started the members of the cluster we saw errors in the log saying the members in AP failed to join or establish a view with the dmgr in Europe. After analysis and testing we concluded that network delays between geographies were the cause. To get around this we deactivated the HA Manager. Doing this had the side-effect of losing session failover because session tokens where no longer replicated between cluster members. When a user is sent to another server they get a message saying the session had expired. By activating sticky sessions with the load balancer we were able to keep the user on the same server, so under normal operating conditions sessions are not lost. In cases where a server goes down, there is still a loss of session when the user is switched to another server, but this is a rare occurence fortunately.
A better ST deployment architecture across distant geographies would be to set up a separate cluster in each geography. It is possible to have a single ST Console govern servers that are not in the same cluster. In our case this means having a cluster in Europe with the dmgr, the ST Console, and 2 ST Proxy servers. And in AP, set up a cluster with a dmgr, but without a ST Console, plus the 2 ST proxy servers. These servers would be registered with the ST Console in Europe. This allows managing policies from one ST Console.