On Thu, Aug 18, 2016 at 1:41 PM, Valentine Sinitsyn < valentine.sinit...@gmail.com> wrote:
> On 18.08.2016 23:49, Andy Zhou wrote: > >> >> >> On Thu, Aug 18, 2016 at 8:34 AM, Valentine Sinitsyn >> <valentine.sinit...@gmail.com <mailto:valentine.sinit...@gmail.com>> >> wrote: >> >> On 18.08.2016 17:42, Russell Bryant wrote: >> >> >> On Thu, Aug 18, 2016 at 2:30 AM, Valentine Sinitsyn >> <valentine.sinit...@gmail.com >> <mailto:valentine.sinit...@gmail.com> >> <mailto:valentine.sinit...@gmail.com >> >> <mailto:valentine.sinit...@gmail.com>>> wrote: >> >> Hi everyone, >> >> Russell, Would HA manager also manage >> ovn-controller >> switch over? >> >> >> Yes, indirectly. The way this is typically handled >> is by >> using a virtual >> IP that moves to whatever host is currently the master >> >> Cool, then ovn-controller does not have to be HA aware. >> >> >> In my understanding, the virtual IP feature in Pacemaker (i.e. >> IPaddr2) works if both active and passive nodes of the >> cluster are >> in the same IP subnet. >> >> For some deployments, this would mean both nodes a located >> on the >> same physical rack. This is not actually a fault-tolerant >> design >> (think blackout). >> >> If I'm getting virtual IP addresses in Pacemaker correct, >> wouldn't >> it be better to make ovn-controller HA aware? That is, have >> a node >> switching command (akin to >> ovsdb-server/connect-active-ovsdb-server) >> and let Pacemaker make use it? >> >> >> I was not planning to have pacemaker manage ovn-controller on >> every host. >> >> OK, makes sense. >> >> Would using a proxy server, such as HAproxy, help? >> > Help in what? > > To provide a single routable IP address for ovsdb clients to connect to. > > >> >> >> If this sounds reasonable, I can take on it probably. >> >> >> In general, I think having ovn-controller able to connect to >> more than >> one database IP seems fine. I don't expect everyone to >> necessarily >> agree on the same HA architecture. >> >> Perhaps it's simple and good enough to add some support for >> multiple IP >> addresses for the southbound database that ovn-controller can >> rotate >> through on reconnect attempts? >> >> As passive ovsdb instance doesn't accept client connections, this >> wouldn't help much if the connectivity between ovn-controller and >> south ovsdb master is broken. But this scenario is likely outside >> current HA architecture either. >> >> >> Yes, something external should change ovsdb-server from backup into >> active. A backup server accepts clinet connections, but rejects any >> "write" transaction that can >> change the database. >> > Pacamaker is a proposed way to do it, as far as I understand. Right. I am still in favor of using floating IP for this release. > > > >> >> In short, yes, having support for multiple IPs in ovn-controller is >> certainly a step forward in the right direction IMO. >> >> >> I agree it could be a worthwhile feature. If we end up implementing this >> feature, I hope we don't statically configure the backup server IP >> address. It may be better >> for the idl client to keep track of current backup server. One possible >> way to implement it is to store the backup connection into the database. >> > Which of the databases? ovn-controller connects to OVS one, and to SB. > Storing this in OVS means the backup server need to know all > ovn-controllers on the net, having this information in SB itself is > somewhat chicken and the egg problem. > I'd think we need store them in both DBs. HA manager or backup server can update the SB first, ovn-controller can then replicate the configurations to its local OVS DB. > Now we store OVN SB location in the OVS database, do we? My initial intent > was store not one, but two addresses, and switch between them. > I don't object we start there. and this may be fine for the situations where active and backup server will always occupy two well known addresses. I just hope we have a plan to to update those addresses in case HA manager launches the backup server with a differnt IP address. > > Besides, don't we also want ovn-northd to support multiple addresses for > NB/SB then? That would be nice too, > > The backup server >> can issue an transaction to record its connection information, before >> replicating. >> > > Valentine > > >> >> Best, >> Valentine >> >> >> >> -- >> Russell Bryant >> >> _______________________________________________ >> dev mailing list >> dev@openvswitch.org <mailto:dev@openvswitch.org> >> http://openvswitch.org/mailman/listinfo/dev >> <http://openvswitch.org/mailman/listinfo/dev> >> >> >> _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
