Probably - if it can be clustered - then it will most likely work in VCS, but you need to explain what you are trying to do as HAProxy already offers HA - that is what the HA in HAProxy stands for, so what are you hoping to achieve by using VCS. Where I have seen VCS being used in the sort of scenrio is where there is a requirement to only load balance across 2 servers for multiple applications and so for instance you have:
Application A load balanced on virtual IPS A1 and A2 which initially reside on server 1 and 2
Application B load balanced on virtual IPS B1 and B2 which initially reside on server 1 and 3
Application C load balanced on virtual IPS C1 and C2 which initially reside on server 2 and 3
where VCS is used to control the virtual IPS so that if for instance server 2 fails, then A2 fails to server 3 and C1 fails to server 1. VCS is very good at handling this, especially when you scale up to more applications and/or servers as you can use service group prequisites to make it very easy to ensure you dont have for instance virtual IPs A1 and A2 running on the same server and use Load balancing to choose where the IP fails when you have more than 1 choice to fail to.
So it is very easy in VCS, for example, to configure 10 servers in a cluster with 40 applications with each application requiring a differering number of servers (ranges from 2 to 8 servers) to load balance across.
Mike
