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Nova Cells: Question about Networking and Storage

asked 2015-02-05 12:24:44 -0500

Mathias Ewald gravatar image

Hi, I am just wrapping my head around the concept of cells. Here two questions I cannot figure out:

Networking: From a couple of Youtube videos and slidedecks on Slideshare I noticed, that every child cell runs its own instance of Neutron. So I end up running kind of the same Nova service but multiple independent Neutron setups. So when I request a new instance from the parent cells nova-api service, I am going to pass it the ID of the network to attach to. But as nova schedules the instance to any cell it controls, how does it work? Is the network created in every child cell with the same ID? But as far as I know Neutron is not aware of any cells. The other option I am seeing is to run a single instance of neutron and share it accross cells.

Storage: Pretty much the same question as before but this time to be answered for volumes.

Any help is appreciated :)

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answered 2015-08-21 03:29:35 -0500

Tosugueur gravatar image

updated 2015-08-21 04:27:50 -0500

In the beginning I would like to say that I share the same questions: about cells, and about the lack of resources on this matter. Probably the "only" community member that gives details about its deployment of cells is CERN (others like Rackspace or NeCTAR do not give much).

According to the openstack architecture guide provided here, CERN has used for:

  • Control: nova-api (that is deployed on api cell as well as compute cells) to launch VMs in local compute nodes
  • Networking: nova-network for networking (flat network) and a pre-registered MAC+IP list associated with each compute node
  • Storage: MySQL database server in each cell in an active/passive configuration with a NetApp for local storage and HA

I still have the same question as you do about neutron. It seems like no one has deployed cells using neutron yet.

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answered 2015-09-07 05:49:03 -0500

sha gravatar image

Hi, when I first install nova cells, I tried to install one neutron-server on the api-cell and share the same AMQP SERVER with the api cell. And each child cell has its own AMQP SERVER. But neutron has some problem sending the 'vif plugging callback' message back to nova-compute, and instances failed to boot. Only when I set vif_plugging_is_fatal=false, nova-compute is able to boot the instance.

Are you able to successfully run instance using nova-cells with neutron service in each child cell? Can you post the link on youtube and slideshare that you mentioned about. I am interested to know how it works with mulitple neutron instances. It seems nova-cells works better with nova-network than neutron.

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answered 2016-08-04 02:38:35 -0500

tim-bell gravatar image

At CERN, we have now deployed cells and Neutron. We have a single Neutron instance across all the cells. Given that we are migrating from Nova network to Neutron without disruption for the users, we are testing this out with a number of cells first. Our Neutron configuration is relatively simple however, just using linux bridge and provider networks for the moment. However, the more sophisticated configurations should work too.

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Asked: 2015-02-05 12:24:44 -0500

Seen: 1,825 times

Last updated: Aug 04 '16