On 05/10/2012 12:46 PM, Dan Wendlandt wrote: > > > On Thu, May 10, 2012 at 12:05 AM, Gary Kotton <gkot...@redhat.com > <mailto:gkot...@redhat.com>> wrote: > > On 05/10/2012 12:55 AM, Sumit Naiksatam (snaiksat) wrote: > > Hi Gary, > > Thanks for initiating this. A couple of comments/questions - > > 1. Do we really need the VIF driver to communicate the agent's > identity; > I am referring to the agent ID being sent by the VIF driver in the > message? In general, I am not sure if there is a need to have > the VIF > driver send messages/notifications in the first place, but I perhaps > it's being included as a capability in the framework? > > At the moment the open source plugins are not aware of the agents. > The agents poll the data base for updates. The agent ID enables a > agent to regsiter with the plugin, this in trrun enables the plugin > to send a update to the specific agent. The update is initiated by > the VIF driver. In my opinion this does the following: > 1. updates the agents as soon as possible regarding a network change > 2. limits traffic on the network > 3. removes the database interface from the agents > > > One important thing to note is that as we move toward achieving nova > parity (which includes security groups, dhcp, port security, L3, NAT) > the amount and type of data shared between the central node and the > agents will take on many different forms. Many of the > existing implementations that we'll be porting over from Nova rely on a > central data store, and my feeling is that the fastest and least bug > prone approach will be to have those agents continue to fetch data from > the database. The biggest win we get from RPC is eliminating polling by > notifying agents about changes via RPC, rather than having them poll the > database to recognize that something has change. This is how Nova works > as well, so I'd focus on using RPC in that fashion first.
On a related note, one of the goals we have for nova in Folsom is to cut down much of this database access in favor of passing objects through rpc. https://blueprints.launchpad.net/nova/+spec/no-db-messaging There are a few different motivators for this. One is efficiency in that it cuts down on how much the database gets hit. Another is security. By removing direct database access from compute nodes, we can more easily reduce the potential impact if a compute node were to get compromised. -- Russell Bryant -- Mailing list: https://launchpad.net/~netstack Post to : netstack@lists.launchpad.net Unsubscribe : https://launchpad.net/~netstack More help : https://help.launchpad.net/ListHelp
