I have 1 SA6000 Active/Passive Cluster and 1 SA4000 Active/Passive Cluster, each cluster has licensing for 1,000 users. I would like to combine these clusters to allow for 2,000 users to access via 1 URL, is anyone aware if this is possible? I have an F5 BigIP available for load balancing if that will work.
We do just what you are suggesting, though we also recently eliminated active/passive clustering, and let the F5 do all the work of failover as well. We didn't find that the value of A/P clustering outweighed the complexity it created.
We currently have 8 6000/6500s behind a F5 LTM in 3 different pools (3 different URLs for different uses of the SAs). Source address persistence is important - we use a persistence timer of 60 minutes. That seems to work OK, though I think we could take it down to 20 minutes (our rekey interval).