Got it. By RPC I was referring to RabbitMQ in particular. That's also the rationale that Rackspace presented at the Portland summit.
Subbu On Oct 3, 2013, at 11:42 AM, Chris Behrens <cbehr...@codestud.com> wrote: > > On Oct 3, 2013, at 10:23 AM, Subbu Allamaraju <su...@subbu.org> wrote: > >> Hi Tim, >> >> Can you comment on scalability more? Are you referring to just the RPC layer >> in the control plane? > > Not just RPC, but RPC is a big one. Cells gives the ability to split up and > distribute work. If you divide hypervisors into different cells, in each > cell you have less connections to rabbit, less work for the host scheduler to > find a suitable hypervisor, etc. You also mentioned 'failure domains' and > that can be a good reason to use cells as well. I felt that the multi-DC or > multi-continent scenario where you want your nova-api endpoints to see ALL > instances (as opposed to multi-region with keystone) was a good use case for > cells. You should want services to talk to each other with low latency. > Each cell has its own rabbit and DB that you can keep 'close by'. Sure, you > can cluster/HA/replicate rabbit and 1 big DB, but those technologies fail and > when the fail, they tend to fail badly. Cells can isolate issues to a subset > of your cloud. > > - Chris > > >> >> Subbu >> >> >> On Oct 3, 2013, at 8:53 AM, Tim Bell <tim.b...@cern.ch> wrote: >> >>> >>> At CERN, we’re running cells for scalability. When you go over 1000 >>> hypervisors or so, the general recommendation is to be in a cells >>> configuration. >>> >>> Cells are quite complex and the full functionality is not there yet so some >>> parts will need to wait for Havana. >>> >>> Tim >>> >>> From: Dmitry Ukov [mailto:du...@mirantis.com] >>> Sent: 03 October 2013 16:38 >>> To: openstack@lists.openstack.org >>> Subject: [Openstack] Cells use cases >>> >>> Hello all, >>> I've really interested in cells but unfortunately i can't find any useful >>> use cases of them. >>> For instance I have 4 DCs and I need single entry point for them. In this >>> case cells are a bit complicated solution. It's better to use multiple >>> regions in keystone instead >>> >>> The only one good reason for cells, which I've found, is to organize >>> so-called failure domains, i.e. scheduling on another DCs in case of >>> failures. >>> >>> Does anyone have different use cases or vision on cells usage? >>> Thanks in advance. >>> >>> -- >>> Kind regards >>> Dmitry Ukov >>> IT Engineer >>> Mirantis, Inc. >>> >>> _______________________________________________ >>> Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack >>> Post to : openstack@lists.openstack.org >>> Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack >> _______________________________________________ >> Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack >> Post to : openstack@lists.openstack.org >> Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack > _______________________________________________ Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack Post to : openstack@lists.openstack.org Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
