For a busy site that's straining its current front end server, we've been offered a variety of load balancing solutions, ranging from hardware load balancing to DNS rotation.
It seems like a dedicated hardware load balancer is the optimal solution; we've played with DNS load balancing and it seems to create some issues. We're looking at balancing two high-end dual Opteron servers initially, but might later have to add one or more additional servers to the mix.
Any insights? The host we are currently with wants $600/mo for the hardware load balancer, which seems pretty high to me.
You might be able to negotiate that lb fee. My host charges us $150 setup fee for a hardware load balancer plus $75 per server per month balanced. So we balance 4 web servers behind a load balancer and the fee is $300 per month.
IPVS (linux software load balancing) works great. I use it in front of a 20 machine http cluster and in front of a smaller application cluster. The real trick is getting the failovers set up the way you want and avoiding any single points of failure. My first web cluster I had everything set where I thought I would need multiple hardware failures before causing an outage - a gateway with a failover, extra machines in the cluster, redundant power, redundant internet connections - I forgot the ethernet switch that all the machines were plugged into.