Load balancers and SQL backups

Taking load off a server to do a backup is not unheard of. How you do that depends entirely on your load balancer. For example, Kemp load balancers have a web API you can call to disable a particular server and haproxy has a pipe based management interface that you can script from a linux shell. I'm sure that pound has an equivalent way off disabling a server but I don't know what that is.

Another popular way to disable a server with haproxy is to have the check action look for a specific file. When you want to disable the server just delete or rename that file. You should be able to easily do this with pound, and it satisfies your requirement of keeping the scripting in our web tier and not calling to the load balancer.