Assuring High Availability
As I mentioned earlier in this article, you can use the backup/restore, synchronization, or detach/attach methods for scaling out; the same methods can also be used for high availability. In addition, you could also exploit failover clustering to guarantee your MSAS databases’ availability. When MSAS is clustered, two physical hosts share the disk resources hosting multi-dimensional files. Only one node of the cluster is active at any time, and the other node can take over if the active node experiences hardware issues. Clustering is an expensive solution because at any given time only one node is serving user requests and the other one is idle. On the other hand, you can fail the cluster over to the passive node in a matter of seconds and no application changes are necessary to direct user traffic to the active node. As with scaling out, you could consider using multiple methods of high availability in tandem, depending on your business needs.