[Engine-devel] Ideas about engine clustering?

[Laszlo Hornyak]

----- Original Message -----
> From: "plysan" <plysab at gmail.com>
> To: "Laszlo Hornyak" <lhornyak at redhat.com>
> Cc: engine-devel at ovirt.org
> Sent: Wednesday, August 21, 2013 5:08:57 PM
> Subject: Re: [Engine-devel] Ideas about engine clustering?
> 
> 2013/8/21 Laszlo Hornyak <lhornyak at redhat.com>
> 
> > Hi,
> >
> > ----- Original Message -----
> > > From: "plysan" <plysab at gmail.com>
> > > To: engine-devel at 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 haven't
> > > found anything.
> > >
> > > I know there will be lots of things to do for engine migrating to
> > clustering
> > > environment. I just want to know what problem need to be solved?
> > > I would like to list the things I think that is needed to do(or solve):
> > > 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 could 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)* *

There are only a very small number of real EJB's in oVirt, almost all and everything is done by singletons created by EJBs. (check InitBackendServicesOnStartupBean, Backend they are the biggest factories of these singletons)
If you made a deeper research in this recently then your information may be more up to date than mine, but while working in various parts of the app I have found tons of local state.

> 
> >
> > >
> > > Any ideas?
> > >
> > > Thanks!
> > >
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> > >
> >
>