On Thu, Mar 15, 2012 at 11:09 PM, coma <coma....@gmail.com> wrote: > Hello, > > I'm a new Pacemaker user and i trying to understand exactly what it can do / > can't do in case of MySQL Replication or DRBD replication. > > I have two MySQl servers, for the moment with a simple Master/Slave > replication, my need is to implement a high availability system with > automated IP and DB fail-over / fail-back (including replication). > > I would like to be able to have 1 node designated as Master and in case of > failure, automatically promote the slave node to master, and when the > initial master will available again do the reverse operation automatically. > > I have compared several solutions and according to my needs (i have two > servers only and i don't want / don't need use solutions like MySQL Cluster > which requires 4 servers), Pacemaker seems the best solution in my case. > > I have to choose between Pacemaker with MySQL replication or Pacemaker with > DRBD replication but it's difficult to find clear explanations and > documentation about the 2 solutions, so i have some questions about it. > If anyone can enlighten me i thank in advance! > > > In the Pacemaker + MySQL replication case: > > I know pacemaker is able to do IP failover and it seems DB failover too(?), > but what type of failure pacemaker can detect? > I know it is able to monitor the network failure (node unreachable), but can > it detect MySQL service failure and promote the slave to master?
Yes. We call the mysql resource agent and react to any failures it detects. > Example: Master node reachable, but database not (mysql service stopped, > access failed->too many connexions, disk full, database read access but > write error...)? > > Can pacemaker do (natively) the reverse operation automatically (When > initial master node or MySQL DB will be available again)? Yes. This is what the http://www.mysqlperformanceblog.com blog is talking about. Pacemaker doesn't actually understand what it is managing, the details are hidden by the RA scripts. > In this case, can it manage the replication? and if not, can i use a > personal shell scipt to do it? > > Else, i have browsing the maillinglist archives and i've seen the Percona > Replication Manager solution > (http://www.mysqlperformanceblog.com/2011/11/29/percona-replication-manager-a-solution-for-mysql-high-availability-with-replication-using-pacemaker/), > somebody he already implemented it in production environment? Is it > reliable? I've not used it myself but I hear good things. > > > In the Pacemaker + DRBD replication case: > > I understand that pacemaker and drbd work very well together and drbd is a > good solution for mysql replication. > In case of master (active node) failure, pacemaker+DRBD promote > automatically the slave (passive node) as master and i have read that drbd > can handle itself the back replication when master node is available again? > can you enlighten me a little more about it? > > I also read that it is recommended to have a dedicated network for drbd > replication, but can i do without? I don't write a lot on my databases, > reading much more, so replication will not be a big charge. > > The big problem i have with DRBD is that i work on RHEL5 and i have read > that i will have to recompile DRBD after each kernel update (there is not a > lot of updates but still some), > is it possible to avoid it? (CentOS DRBD packages maybe?) > > Somebody has already been problems with RHEL updates and DRBD/Pacemaker? RHEL5 is getting on a bit, its version of glib is too old to even build pacemaker there anymore. What about using RHEL6 which even ships with pacemaker? > > Thank you in advance for any response, and sorry if my english is not very > good. > > > > _______________________________________________ > Pacemaker mailing list: Pacemaker@oss.clusterlabs.org > http://oss.clusterlabs.org/mailman/listinfo/pacemaker > > Project Home: http://www.clusterlabs.org > Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf > Bugs: http://bugs.clusterlabs.org > _______________________________________________ Pacemaker mailing list: Pacemaker@oss.clusterlabs.org http://oss.clusterlabs.org/mailman/listinfo/pacemaker Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org
