Hi Tim, I'd also like to know what happens above 1000 hypervisors that u think needs cells?
>From experience at y! we actually start to see the nova-scheduler (and the >filter scheduler mainly) be the problem (at around ~400 hypervisors) and that >seems addressable without cells (yes it requires some smart/fast coding that >the current scheduler is not designed for, but that seems manageable and >achievable) via reviews like https://review.openstack.org/#/c/46588, >https://review.openstack.org/#/c/45867 (and others that are popping up). The >filter scheduler appears to scale linearly with the number of hypervisors, and >this is problematic since the filter-scheduler is also single-CPU bound (due >to eventlet) so that overall, makes for some nice suckage. We haven't seen the >RPC layer be a problem at our current scale, but maybe u guys have hit this. >The other issue that starts to happen around ~400 is the nova service group >code, which is not exactly performant when using the DB backend (we haven't >tried the ZK backend yet, WIP!) due to frequent and repeated DB calls. It'd be interesting to hear the kind of limitations u guys hit that cells resolved, instead of just fixing the underlying code itself to scale better. -Josh From: Subbu Allamaraju <su...@subbu.org<mailto:su...@subbu.org>> Date: Thursday, October 3, 2013 10:23 AM To: Tim Bell <tim.b...@cern.ch<mailto:tim.b...@cern.ch>> Cc: "openstack@lists.openstack.org<mailto:openstack@lists.openstack.org>" <openstack@lists.openstack.org<mailto:openstack@lists.openstack.org>> Subject: Re: [Openstack] Cells use cases Hi Tim, Can you comment on scalability more? Are you referring to just the RPC layer in the control plane? Subbu On Oct 3, 2013, at 8:53 AM, Tim Bell <tim.b...@cern.ch<mailto: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<mailto: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<mailto:openstack@lists.openstack.org> Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
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