I've added a wiki page on Engine HA. http://www.ovirt.org/Features/Engine_High_Availability
Please add your comments, we'll try to make this an ongoing effort.

On Sat, Aug 24, 2013 at 3:25 PM, Liran Zelkha <liran.zelkha@gmail.com> wrote:
IMHO EJB clustering is not the direction we should take, especially considering our IoC plans (see http://gerrit.ovirt.org/#/c/5575/).
QuartzScheduler can be easily fixed by using a DB for Quartz configuration. We had such a discussion a few weeks ago.
mod_jk is probably better for our HA.
Postgres clustering should probably be a different task, as it's more infra and less code.

Another thing to consider is locking, currently done using synchronized, and will need to be changed somehow (probably using Infinispan).

On Aug 22, 2013, at 10:22 AM, Itamar Heim wrote:

On 08/21/2013 10:27 PM, plysan wrote:

2013/8/22 Itamar Heim <iheim@redhat.com <mailto:iheim@redhat.com>>

   On 08/21/2013 11:08 AM, plysan wrote:

       2013/8/21 Laszlo Hornyak <lhornyak@redhat.com
       <mailto:lhornyak@redhat.com> <mailto:lhornyak@redhat.com


            ----- Original Message -----
             > From: "plysan" <plysab@gmail.com
       <mailto:plysab@gmail.com> <mailto:plysab@gmail.com
             > To: engine-devel@ovirt.org
       <mailto:engine-devel@ovirt.org> <mailto:engine-devel@ovirt.org
             > Sent: Wednesday, August 21, 2013 3:49:31 PM
             > Subject: [Engine-devel] Ideas about engine clustering?
             > Hello, guys:
             > I'm trying to make a jboss clustering environment for
       engine. But
            felt the
             > difficuty too.
             > So I want to know if any one is working on this? I
       googled it and
             > found anything.
             > I know there will be lots of things to do for engine
       migrating to
             > environment. I just want to know what problem need to be
             > I would like to list the things I think that is needed
       to do(or
             > 1. run jboss in standalone-ha mode or domain mode.
             > 2. add @Clustered annotation to each EJB, I think this
       will solve the
             > replication problem in cluster, probably lots of details
       in it.
             > 3. QuartzScheduler problem, only one node running a
       scheduler is
            enough at a
             > time instead of each node running one.
             > 4. use mod_cluster to handle load balancing.
             > 5. postgresql clustering.

            For failover it sounds like a plan, just wondering if this
            solve load balancing problems as well.
            Ovirt is generating a big load on the DB and I would be really
            interested if SQL DB clustering could solve the issues.
            It would be great if it could, big part of the scalablity
       issue is
            the evil things we did against that poor database.

             > 6. There should be more, but hope anyone can think about
       it :D

            There are tons of data structures that are used in oVirt
       that store
            state. You will have to hunt all of these down and replace
       with a
            data structure that is shared between the cluster memebers.
       This may
            be a big lot of work from many parts of the application.

       Indeed, and like Yair Zaslavsky said, we can put the data
       structure in
       infinispan cache, but clustered EJB can do the same thing for
       us, right?
       If all those state values are inside EJBs. (iirc)**

             > Any ideas?
             > Thanks!
             > _________________________________________________
             > Engine-devel mailing list
             > Engine-devel@ovirt.org <mailto:Engine-devel@ovirt.org>
       <mailto:Engine-devel@ovirt.org <mailto:Engine-devel@ovirt.org>__>
             > http://lists.ovirt.org/__mailman/listinfo/engine-devel


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   unless you need the load balancing, just for HA, hosted-engine
   should cover your needs?

I think failover and more scalability  is what i am interested here.
Just thinking about the possibilities :)
Imagine engine would never get restarted from outside view. Cool isn't it?

active/passive failover you should get from hosted-engine (yes, with some downtime)
scalability and active-active would be great. iirc, juan looked at implications of doing this a while back
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