Hi,
Ruzsinszky Attila wrote:
Hi,
A MySQL Multi-Master architecture for a 2 node setup brings a lot of
configuration and administration overhead and has no conflict detection or
resolution. Integrating such a setup with Pacemaker only adds to the
Yes, I found it.
The real story: I want to learn clustering with a 2 node failover cluster.
I configured the cluster by DMC (DRBD Management Console).
I used the GUI configuring a MySQL service. It was almost unsuccessfull
which wasn't a surprise for me. After that I started to read some HowTo,
WEB page, etc. for help. I found someone from #mysql-nbd channel who
helped me and adviced me using M-M MySQL config but he doesn't know
almost anything about Pacemaker (He uses RH cluster).
And now (officially) RHCS can also use Pacemaker
http://theclusterguy.clusterlabs.org/post/1551292286
After we did the working M-M config I started pacemaker and I could see
MySQL is working. I could connect to the commonIP and I could create a
test DB. Everything seemed all right until I put standby the master node
(from pacemaker point of view). In that moment mysqld started to "blinking"
between working and not working state because pacemaker always restarted
the process.
In the messages file I clould see some lines about missing privs. (RELOAD
and SUPER).
So I'm here now.
Yeah, like I said, Master-Master and Pacemaker without a proper resource
agent will cause issues.
server. Even the LSB script doesn't handle a Multi-Master setup. You'd have
to write a custom resource agent, and it would probably fit your setup and
your setup alone, meaning it couldn't be widely used for other setups, I
know I had to make some modifications to the mysql resource agent and those
changes were specific to my setup.
No, I don't want to write scripts. I'm not a programmer. I just want
to try out a
new tech for MySQL clustering except MySQL+DRBD.It is clear for me
theoretically. The files of mysqld reside on the common dir. which was switched
by DRBD. Is that right?
Yes.
MySQL Cluster is a choice, it could be integrated with Pacemaker, although I
Now I don't want MySQL Cluster. I think it is a bigger task for me.
Anyways, this is just to get a feel for what's involved in the process, and
how Pacemaker would fit the picture, at least from my point of view.
OK
I would recommend all questions related to MySQL Cluster, Replication,
Multi-Master be directed to the appropriate mailing lists though, and if you
As I mentioned I've got an M-M config from #mysql-nbd.
The recent problem is MySQL (M-M) + Pacemaker.
Back to square one, don't pass go, don't collect $200. No resource
agent, big problems. Now let me explain this, a 2-node Multi-Master
MySQL setup means setting up every node as both Master and Slave, node
1's Master replicates asynchronously to node 2's Slave and node 2's
Master replicates asynchronously to node 1's Slave. The replication
channels between the two are not redundant, nor do they recover from
failure automatically and you have to manually set the
auto-increment-increment and auto-increment-offset so that you don't
have primary key collisions.
Now imagine a resource agent and what it should do to keep the resources
up. First you need to check periodically (monitor) the replication
channels, if they fail, you must determine which node has the most
recent information and make sure that first it's information is sent to
the other node via the Slave replication channel, then activate the
reverse Master-Slave channel, otherwise you'd be in a MySQL
'split-brain' situation, where each node has information written to it
and the database now contains different views on each server. Looking at
how DRBD handles these kinds of things is one way to go about it, but
... it's a huge task and there are a lot of things that can go terribly
wrong.
So again, for the third time, the problem is not the Multi-Master setup,
nor it is Pacemaker, it's just a very specific use case for which a
resource agent wasn't written.
Regards,
Dan
want to write a resource agent for a Multi-Master setup, by all means, do
share :)
No, I don't want. I'm a beginner both in clustering and MySQL.
Hope this helps.
Yes, of course.
BTW.
If I want to solve the above problem can you help me?
Of course with my
strict error messages, config files, etc. I "feel" my M-M config is not
rock stable (I was able to brake the IO or SQL "channel" between the
two mysqld processes) so I don't know whether I want this type of setup.
TIA,
Ruzsi
_______________________________________________
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://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
--
Dan FRINCU
Systems Engineer
CCNA, RHCE
Streamwide Romania
_______________________________________________
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://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
