i have two linux machines, one has two ethernet card with eth0: local ip and eth1: global ip, and the other has only one with eth0: local ip

Can i use serial port to connect the two machines for heartbeat communication? or i must use two machines with two ethernet cards for each?

if i can do with current machines, can anybody help me the detailed configurations? i want to try the heartbeat with httpd to work like when the httpd on one machine is down the other machine will startup with the virtual ip.

any help is appreciated.

Thank you

Usually the serial communication is meant to transmit heartbeat signals between the machines. The second ethernet card is needed for data replication through DRDB: two additional NICs are connected by a cross-over cable to speed-up data replication, being completely independent from the local network.

On the Linux-HA site you will find plenty of tutorials and articles about the setup. You can start from a general overview with configuration examples and a very useful heartbeat diagram, here.