Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hello. First of all, I'd like to salute everybody in this list, as this is my first message to it. As you might guess, I'm a total newbie here, but I'll try to cooperate and help as much as I can. Now I'd like to raise one question. Basically, it is quite simple: Does DRBD support more than two secondary nodes? I guess it doesn't. I've never seen a configuration example with more than two nodes (primary + secondary) and I thing that (for what I understood in the documentation) more than one secondary is not supported because of the high network traffic load. But I'm asking because I have seen an email (http://osdir.com/ml/linux.highavailability.devel/2006-06/msg00143.html) saying that the support of more than two nodes was intended... and that was two years ago so maybe I didn't find the right web page :) Now, if you have more time, I'll try to detail my problem: I have currently two Xen virtual machines running into a physical machine. Each of the virtual machines is running a MySql instance, each of which write the data in a drbd partition (thus the Mysql data are the same). Over this, I have a Virtual IP controlled by HeartBeat. Now, if a machine or a mysqld process fails, all the MySql petitions are redirected to the other machine. As you may have foreseen, the Drbd resource is controlled by Heartbeat as well. I think this is a very typical configuration (I did more or less what is explained here: http://marksitblog.blogspot.com/2007/07/mysql-5-high-availability-with-drbd-8.html). You should be able to see (if imageshack still keeeps it) a simple diagram of what I currently have in the following address: http://img388.imageshack.us/img388/6832/pict01tv3.png As I said Both machines are Xen Virtual machines but it did't matter much... for the moment. Now I'd like to replicate the structure to another physical machine, to have even more security (higher availability) and I don't know exactly how I could do it... It would be nice if Drbd could replicate in more than two partions. You can see what I want to get in http://img379.imageshack.us/img379/2812/pict02hp5.png. What I want is tho have everything running (is possible) in monitor01:database01. If something in database01 fails, have heartbeat moving everything to database02, and keep working connecting to that machine (in a transparent way to the MySQL clients), but if monitor01 fails, or database01 and database02 fails I have to move to monitor02. And there comes my problem. I don't know which would be the best way to have the same data in all the database0x machines. I thought in having a DRBD unit in monitor01 and monitor02, and then mounting it (via NFS or something like that) in the database0x machines. Something like: http://img352.imageshack.us/img352/2688/pict03vv6.png but I don't know if it is good idea. Could anyone give me a hint, or even a personal opinion? Thank you in advance!!