Instant Messaging and High Availability

Instant Messaging provides a Sun Cluster agent, but it does not support Veritas Cluster Service. You can also create a “more available” environment by deploying redundant Instant Messaging multiplexors, and by taking advantage of the Instant Messaging watchdog process.

Instant Messaging High Availability Overview

Configuring Instant Messaging for high availability (HA) by using the Sun Cluster agent provides for monitoring of and recovery from software and hardware failures. The high availability feature is implemented as a failover data service, not a scalable service, and is currently supported only on Solaris.

You can have multiple Instant Messaging nodes in an HA environment using the same SMTP server.

Before implementing an Instant Messaging HA environment using the Sun Cluster agent, decide which of the following HA deployments best meets your needs.

• Mixed HA Environment. This deployment consists of a local configuration and binaries, and global runtime files. The advantage to this setup is that upgrading Instant Messaging requires minimal downtime because you can upgrade on nodes where Instant Messaging is offline. The disadvantage is that you need to ensure that the same configuration and version of Instant Messaging exists on all nodes in the cluster. In addition, if you choose this option, you need to determine whether you will be using HAStoragePlus or the cluster file system for global runtime files.

• Global HA Environment. This deployment consists of a global configuration, binaries, and runtime files. This setup is easier to administer, but you need to bring Instant Messaging down on all nodes in the cluster before upgrading.

Using Multiple Instant Messaging Multiplexors

In an Instant Messaging deployment of multiple multiplexors, if one multiplexor fails, Instant Messaging clients are able to communicate to the back-end server through another available multiplexor. Currently, you can only configure multiple multiplexors to speak to a single instance of Instant Messaging server. You cannot configure multiple multiplexors to talk to multiple instances of Instant Messaging.

Using the Instant Messaging Watchdog Process

Instant Messaging includes a watchdog process, which monitors the Sun Cluster agent, and restarts the services that become unavailable for some reason (such as server lockup, crash, and so forth). In the event that you configure the watchdog process, and an Instant Messaging component stops functioning, the watchdog process shuts down then restarts the component.