Sure. I am running such a setup. You can couple services like squid to the availability of an IP address. The IP addresses are then handled by heartbeat and only on the host having the right IP squid is started. Works almost perfectly. I have one important remark: Linux HA is not exactly "install-and-run". I strongly recommend to test the approach in a non-production setup and emulate the failures you want to circumvent. Otherwise, many strange things may happen. I can give more details if interested.Can we make heartbeat between two squid hosts then?
Yours, Jakob Curdes