[chillyjim]

It really depends on your environment but in general the practical limit is 4 nodes to a cluster before sync traffic starts to degrade performance. There is a lot that can be tuned to increase performance (Like you really don't need to sync http in most cases) but a 4-node cluster still seems to be as far as you can go.

Pre-R65 (I haven't checked R65 yet) the limit was 6 nodes. IIRC ClusterXL on VPN-1 (Not VSX, which is very different) was QA'ed to 8-nodes.

As cciesec2006 points out, think before you jump into the active/active... clustering vs just a simple HA design as it is harder to debug.