Hi, I'm a student and as a graduating project I chose to set up a high availability system with load balancing. Two load balancers (one as a backup...) provide connections to two application servers running a webserver, sql and perhaps some other services. These application servers get their content from two data servers running a nfs. I followed the howto on setting up a highly available and loadbalanced apache server and the one about a highly available nfs server (both written by Falko Timme). All went well except when rebooting after all was set up, I lost all functionality on the data servers. The screen output was completely messed up, and the system didn't respond anymore until I disabled heartbeat. My question is: when BOTH data servers go down, is the nfs lost and if so, why? Is there a solution? I've set up my computers in a network lab of my university where also other student are working. There's a good chance at least one of those students will power off my setup and I don't want all my work disappear at the flip of a switch...
Does nfs-server get started when the system is booted? Do you see it in the output of Code: ps aux ? Any errors in the log files?
First of all, because of the total loss of the data servers(well, I'm new to all of this, perhaps it could be saved ;-)), I ended up re-installing them. I did not save the error logs so I cannot provide you with that information. At the moment the nfs cluster is working like a dream, but I never rebooted both servers at the same time. I only tested if the nfs still worked when one server was down. The nfs-server is started at boottime and no errors are generated. Since I don't know what the outcome will be, I'm not keen on shutting both of them down. But reading between the lines: your answer suggests that the setup should work when both servers go down and are rebooted at the same time?
In general, a cluster configuration should be started one-by-one if both servers went down. It's a bad idea to make both servers fight who's 1st to take precedence. I am not familiar with this howto, but as a seasoned sysadmin on linux clusters, thought I'd give you this advise.
@martinfst: I appreciate your input. Being a student, any information is welcome, especially from experts like you and Mr. Timme. I'm going to set a small time delay at boottime on one server to avoid that problem. Hopefully it helps.
