Chapter Review

     

When we introduce additional data centers or extended distances between nodes in a cluster, we need to start thinking about additional solutions to our cluster that go beyond Serviceguard. Although the technologies we have considered here are in addition to Serviceguard, they share the same high availability principles and ideas with Serviceguard. As such, the overall ideas of these solutions should be familiar to a Serviceguard administrator, although when we start to introduce concepts such as physical data replication using tools such as HP Continuous Access XP Extended. We then get into a whole new sphere of additional technologies including advanced disk arrays and SANs. We should have at least an appreciation of these technologies, if not a detailed understanding. At the heart of all these new technologies is the need to keep our data available for as much time as possible. Additional data centers and extended distances throw some interesting technological and logistical challenges. A key thing to remember is to never have a Single Point Of Failure if you can at all achieve it.