Re: [ovirt-users] Two ovirt-engine manage one hypervisor

On Thu, Jun 16, 2016 at 10:13 AM, Michal Skrivanek <michal.skrivanek(a)redhat.com&gt; wrote: > > On 16 Jun 2016, at 09:07, Yaniv Kaul <ykaul(a)redhat.com&gt; wrote: > > > > On Thu, Jun 16, 2016 at 9:29 AM, Yedidyah Bar David <didi(a)redhat.com&gt; wrote: >> >> On Thu, Jun 16, 2016 at 9:10 AM, Yaniv Kaul <ykaul(a)redhat.com&gt; wrote: >> > >> > >> > On Thu, Jun 16, 2016 at 8:53 AM, Yedidyah Bar David <didi(a)redhat.com&gt; >> > wrote: >> >> >> >> On Thu, Jun 16, 2016 at 5:33 AM, Sandvik Agustin >> >> <agustinsandvik(a)gmail.com&gt; wrote: >> >> > Hi users, >> >> > >> >> > Good day, is it possible to configure two ovirt-engine to manage one >> >> > hypervisor? My purpose for this is what if the first ovirt-engine >> >> > fails, >> >> > I >> >> > still have the 2nd ovirt-engine to manage hypervisor. >> >> > >> >> > is this possible? or any suggestion similar to my purpose? >> >> >> >> The "normal" solution is hosted-engine, which has HA - the engine >> >> runs in a VM, and HA daemons monitor it and the hosts, and if there >> >> is a problem they can start it on another host. >> >> >> >> There were discussions in the past, which you can find in the list >> >> archives, >> >> about running two engines against a single database, and current bottom >> >> line >> >> is that it's not supported, will not work, and iiuc will require some >> >> significant development investment to support. >> >> >> >> You might manage to have an active/passive solution - install an engine >> >> on two machines, configure both to use the same remote database, but >> >> make sure only one of them is active at any given time. Not sure if >> >> that's >> >> considered "fully supported", but might come close. > > > even when you make it work when cert issues are sorted out, you need to be > very careful not to bring both engines up managing a same host, they will > fight over it and the monitoring is going to be received only by one of the > engines, which in turn may cause HA VMs restart and split brains all over > the place. And, IIRC from previous discussions, also internal caches etc. But this is not something specific to ovirt-engine - many services have similar restrictions, and common clustering tools allow handling them. > >> > >> > >> > That's not enough - they need to share the same set of certificates... >> >> Best is to simply clone the machine after initial setup then change >> what's needed, or backup/restore only files (engine-backup --mode=backup >> --scope=files). >> >> Didn't check, but I do not think they actually need all the certs of >> all hosts - that is, that it's not mandatory to keep /etc/pki synced >> between them after initial setup. Didn't try that myself. > > > I'm not sure what happens when you provision a host from Mgmt A, then move > to Mgmt B and provision another from it: > 1. Mgmt A won't be aware of that host, from cert req perspective. May not be > such a big deal - donno. > > 2. Can Mgmt A provision another host? Need to ensure the certificate serial > numbers are OK, etc. > > They really need to share the CA DB. Even keeping /etc/pki synced, or mounted from each one before starting the engine and umounting when stopping, should not be too hard. > The backup-restore sounds like good approach to me. > Y. > >> >> > Y. >> > >> >> >> >> >> >> You can find on the net docs/resources about creating a redundant >> >> postgresql cluster. >> >> >> >> Best, >> >> -- >> >> Didi >> >> _______________________________________________ >> >> Users mailing list >> >> Users(a)ovirt.org >> >> http://lists.ovirt.org/mailman/listinfo/users >> > >> > >> >> >> >> -- >> Didi > > > _______________________________________________ > Users mailing list > Users(a)ovirt.org > http://lists.ovirt.org/mailman/listinfo/users > > -- Didi _______________________________________________ Users mailing list Users(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/users