There is quite a bit of interest in different techniques for using multiple AW/HDS servers with a single CUIC instance, for a number of reasons.

One reason people typically want to use multiple AW/HDS servers is to spread the load from a CUIC instance to multiple data sources. I've already blogged in the past about how you can set this up using the host file on the CUIC Web server to point different CUIC servers to different data sources.

I recently received another question regarding whether it's possible to point a single CUIC server to multiple AW/HDS servers for failover purposes. While this isn't natively supported, there are a couple of ways you can do this.

The first, most obvious way, is to set up multiple data sources and then create another set of reports which point to the alternate data source. This has the advantage of being simple, and requires no intervention from administrators, but it requires the users to know which report to launch.

Another option is to change the datasource to point to another server when it goes down. This will let users continue to run the same reports, but requires an admin to go in and update the data source when one goes down. The admin has to keep the security information handy or remember it, which can also be a problem. You'll also have to set the data source back to original settings once the AW/HDS is back up.

The third option is to use a host file as in the post I linked to above. You can set up an alias on the Web server, even if you're using the same AW/HDS for all CUIC Web servers. Then you can use that alias to redirect traffic to and from that data source as needed.

Now, there are two ways to redirect traffic. One, you could go in and edit the host file on the CUIC Web servers to point to the backup data source. This requires editing and saving the host file, which is a pretty simple operation. Again, you'll have to change it back once the original data source is back online.

Another option is to point that alias to a load balancer which automatically keeps track of which AW/HDS to send traffic to. That is, instead of pointing CUIC directly to the AW/HDS, you can point it to a load balancer which directs CUIC to the correct AW/HDS. This has the advantage of being completely automatic, which is probably what people would like to do. Keep in mind that I have never set this up myself, but I see no technical reason why this should not work. If you do try it, please contact me at @ciscojason on Twitter.