As the Asterisk server is most likely highly critical to business, we want to ensure that restoring from backups rarely happens and in the event of losing a machine when an administrator isn't available, we have some sort of failover system in place. In order to achieve this, we apply redundancy and load-balancing techniques to ensure that our infrastructure has the resources to handle the data it needs to process.
In the event of a component failing, we would like to ensure that we don't lose services. Ideally, the users of the system should never know there was any failure and the administrator should get the failed system back online or replace it at the next convenient moment. This sort of forward planning is essential for maintaining a service that will be used as extensively as Asterisk often is.
Take the example of the 24-hour call center. If we have a business that relies on the telephony system in order to generate revenue, then the loss of that service is a...