Re: [ovirt-users] Max amount of datacenters per ovirt engine

Op 28 apr. 2016 om 13:55 heeft Michal Skrivanek <michal.skrivanek(a)redhat.com&gt; het volgende geschreven: >> On 26 Apr 2016, at 16:48, Martin Sivak <msivak(a)redhat.com&gt; wrote: >> >> @awels: to add another layer of indirection via a dedicated >> hosted-engine per outlet seems a little much. we are talking about 500 * >> 4GB RAM at least in this example, so 2 TB RAM just for management >> purposes, if you follow engine hardware recommendations? > > I would not go that far. Creating zones per continent (for example) > might be enough. > >> At least RHEV states in the documentation you support up to 200 hosts >> per cluster alone. > > The default configuration seems to only allow 250 hosts per datacenter. > > # engine-config -g MaxNumberOfHostsInStoragePool > MaxNumberOfHostsInStoragePool: 250 version: general yep, but that liit is there because within a DC there is a lot of assumption for flawless fast enough communication, the most problematic is that all hosts need to access the same storage and the monitoring gets expensive then. This is a different situation with separate DCs, there’s no cross-DC communication. I would guess many DCs work great actually. Too many hosts and VMs in total might be an issue, but since the last official updates there were a lot of changes. E.g. in stable state due to VM status events introduced in 3.6 the traffic required between each host and engine is much lower. I would not be so afraid of thousands anymore, but of course YMMV > > -- > Martin Sivak > SLA / oVirt > >> On Tue, Apr 26, 2016 at 4:03 PM, Sven Kieske <svenkieske(a)gmail.com&gt; wrote: >>> On 26.04.2016 14:46, Martin Sivak wrote: >>> I think that 1000 hosts per engine is a bit over what we recommend >>> (and support). The fact that all of them are going to be remote might >>> not be ideal either. The engine assumes the network connection to all >>> hosts is almost flawless and the necessary routing and distance to >>> your hosts might not play nice with (for example) the fencing logic. >> >> Hi, >> >> this seems a little surprising. >> >> At least RHEV states in the documentation you support up to 200 hosts >> per cluster alone. >> >> There are no documented maxima for clusters or datacenters though. >> >> @awels: to add another layer of indirection via a dedicated >> hosted-engine per outlet seems a little much. we are talking about 500 * >> 4GB RAM at least in this example, so 2 TB RAM just for management >> purposes, if you follow engine hardware recommendations? yeah. currently the added layer of manageiq with HEs everywhere is not that helpful for this particular case. Still, a per-continent split or per-low-latency-area might not be a bad idea. I can imagine with a bit more tolerant timeouts and refreshes it might work well, with incidents/disconnects being isolated within a DC >> >> But I agree, ovirt does not handle unstable or remote connections that right. but most of that is again per-DC. You can’t do much cross-DC though (e.g. sharing a template is a pain) Thanks michal >> well, so you might be better of with hundredths of remote engines, but >> it seems to be a nightmare to manage, even if you automate everything. >> >> My personal experience is, that ovirt does scale at least until about >> 30-50 DCs managed by a single engine, but that setup was also on a LAN >> (but I would say it could scale well beyond these numbers, at least on a >> LAN). >> >> HTH >> >> Sven >> >> >> _______________________________________________ >> Users mailing list >> Users(a)ovirt.org >> http://lists.ovirt.org/mailman/listinfo/users > _______________________________________________ > Users mailing list > Users(a)ovirt.org > http://lists.ovirt.org/mailman/listinfo/users