On: Introducing Nebula One private cloud system

[keypusher]

I think the idea is to have multiple nebula controllers, one per rack or so? From 2nd page of The Register article:

"You can run a cloud with a single Nebula One controller, but the system was designed to have multiple controllers for high availability and resiliency, says Kemp. The Cosmos operating system can currently span as many as five controllers in a single OpenStack controller domain and automatically load-balances work across controllers and the five racks of servers attached to them. With those five racks, you can have on the order of 2,500 cores and 5PB of storage, depending on the servers you pick."

http://www.theregister.co.uk/2013/04/02/nebula_one_openstack...

[Swannie → keypusher]

Yes, I think we both read that article correctly.

I'm saying that a rack full of servers is all hooked up to a single controller. You then have multiple, interconnected controllers, each one connecting a rack of servers. This is meant to give you HA and resiliency.

However, that is only true if the switch control plane is separate from the x86 hardware running in the controller (because, here we're getting HA and redundancy against the risk of controller hardware failure). I'd hope or expect that to be the case, because Nebula has smart people, but I don't see any material to that effect, yet.

(Typically a DC server farm will have two switches per rack of servers, with a dual-homed server having a connection into each. Therefore if one switch dies, you still have a redundant data path (though, only half the bandwidth)).

[vishvananda → Swannie]

This is correct. The switch will continue to work if the x86 hardware fails. In this case the other controllers will take over management of the servers that are plugged in to the controller with the failed x86 hardware.