Wow, Bob, this is awesome...first thing I did was copied this to a file /home/rado/bobsHAsetup as to keep it's entirety. Thx for this. I have been looking around the web at HA stuff and really hard to see the forest because of the trees and it seems that you already have setup what I want to do! Reading thru this I keep asking myself why this couldn't apply to what I am doing. Can you see why this wouldn't do it? I want to try your config here if you don't mind. gotta pick thru it first tho... > John, > > HA info: > > http://www.linux-ha.org/ > > You might want to look into this before trying to roll your own. > > What I did: > > I am at the Kennedy Space Center, and what we did was a somewhat dumbed > down version of HA and heartbeat. > > I have two machines, essentially web servers for MRTG. You use the term MRTG and the definition I get is Multi Router Traffic Grapher, a tool to monitor the traffic load on network-links. Is this what you mean is this instance? > Each machine has > two ethernet interfaces. The eth0 interfaces are connected to a common > switch, the eth1 interfaces are connected together via a crossover > cable. I understand this and think I have the hardware on hand...nope gotta hustle up a crossover > At any given time, only one machine is active. It remains active as > long as it can ping the upstream router. If it fails to ping the ...upstream router...in my case the zoom??? > upstream router (tries every 10 seconds) it will send a command via rsh > or ssh thru the dedicated link to the slave telling him to become the > master. Both machines also ping each other via eth0 and eth1 and if the > slave determines that the master is not responding (loses both paths) it > will automatically assume the master's role. > > All interfaces have unique IP addresses. The eth0 interfaces are > visible to the world, but the eth1 interfaces are only visible to each > other. The eth1 channel is used to issue remote commands between the > two boxes. The master will also have an aliased IP address on eth0 that > is DNS registered and used by the rest of the world to access the server > (that was the key!). When a switch-over occurs, that aliased address is > removed from the master and added to the slave. This is where ARP > caching becomes a problem. We have Cisco routers upstream and the ARP > caches need to be cleared before traffic will pass to/from the aliased > IP address. > > The router's ARP cache can be cleared with: > > ping -q -c 1 -b -I $COMMONIP $NETWORK > /dev/null 2>&1 > > Where $COMMONIP is the aliased IP address and $NETWORK is the network > mask. I don't how to do this for any other network gear (i.e your > modem). That was the other key! I will have to check into this and my equip. > > The master-to-slave and slave-to-master decision tree is pretty > convoluted and more than likely will be different than yours. > Essentially, whichever machine can see the most (via ping) is the > master. If both see everything, then the one designated as the master > is the master and the other is the slave. As long as the dedicated link > is up, the one becoming the master can tell the other, via rsh, ssh, > etc. A background script runs on each machine every 10 seconds that > does all of the pinging. later on I will need to talk over the scripts w/you please > > Somewhat confusing, but I hope it helps. > > Bob... rather than look and scour the web and go blind trying to decide which way to go I think I would like to try your config if you don't mind. Bob, how are you achieving redundancy between the 2 boxes?? btw, a very confusing issue and you really presented it like it was kids stuff! thx, john rose -- rado <rado@xxxxxxxxxxxxxxx>
