On 21/06/11 13:41, Dejan Muhamedagic wrote:
Hi,
On Thu, Jun 02, 2011 at 08:44:46AM +0100, Luke Bigum wrote:
Hi list,
I have a conceptual question about making Pacemaker treat some resources
a lot more important than others. I'm afraid the answer is going to come
back "sorry you can't", but I just want to confirm.
You were (most probably) right :)
But it sounds interesting. Now, if java is not so important, why
do you run it in the cluster?
Thanks,
Dejan
Very good question :) The Java is our in-house software deployment agent
in which we also deploy MySQL, as well as our own code. At design time
it was easier to add our Java agent to Pacemaker rather than code
cluster awareness into it. Unfortunately that decision was bitten us a
few too many times now in various ways, including the chicken and egg
situation where the Java agent needs to be able to control the cluster
(unmanage MySQL to upgrade it) and is itself controlled by the cluster.
Our way forward now is to code Pacemaker awareness into our agent and
run it on every node.
-Luke
I have a simple 2 node cluster that runs two services (MySQL and a Java
daemon) on top of network attached storage that can float between both
nodes. CRM config looks a bit like:
node node1
node node2
primitive lsb:mysql mysql
primitive lsb:java java
primitve lsb:storage storage
colocation mysql_with_storage inf: mysql storage
colocation java_with_storage inf: java storage
order mysql_after_storage: storage:start mysql:start symmetrical=true
order java_after_storage: storage:start java:start symmetrical=true
I've got the interesting requirement that mysql is vastly more important
than the java resource. The java has to run on the same server as mysql.
Also, if mysql is stopped/unmanaged, the java should still be running on
what would be the correct node for mysql. I've mostly achieved this by
colocating the java and mysql to the underlying storage.
It gets tricky when we start simulating hard failures. If we simulate a
hard error with mysql, the storage moves to another node, then mysql and
java, and everything's great. What I don't want is the opposite to
occur. I don't want any hard error with java to make the mysql move, as
I consider the mysql more important than java and I don't want to outage
mysql if the java has a problem. I'd love for the mysql to stay running
where it is and have an administrator come along and cleanup what's
wrong with the java.
I guess I want to somehow describe the java resource as "not as
important" as mysql, and this is what I don't think is possible. I know
I'm talking about very edge cases by simulating hard errors (eg: monitor
return code 5), but it'd be nice to achieve.
Any thoughts?
Thanks in advance,
-Luke
--
Luke Bigum
Information Systems
luke.bi...@lmax.com | http://www.lmax.com
LMAX, Yellow Building, 1A Nicholas Road, London W11 4AN
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_______________________________________________
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
_______________________________________________
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
--
Luke Bigum
Information Systems
luke.bi...@lmax.com | http://www.lmax.com
LMAX, Yellow Building, 1A Nicholas Road, London W11 4AN
The information in this e-mail and any attachment is confidential and is
intended only for the named recipient(s). The e-mail may not be disclosed or
used by any person other than the addressee, nor may it be copied in any way.
If you are not a named recipient please notify the sender immediately and
delete any copies of this message. Any unauthorized copying, disclosure or
distribution of the material in this e-mail is strictly forbidden. Any view or
opinions presented are solely those of the author and do not necessarily
represent those of the company.
_______________________________________________
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
