Hi Han, ovsdb-client backup and restore work as expected. Sorry for the false alarm. I messed up with the container. When restore the snapshot for nb-db, sb-db is updated accordingly by ovn-northd.
I think this man page should be updated saying RAFT cluster is also supported by backup and restore. http://www.openvswitch.org/support/dist-docs/ovsdb-client.1.txt Thanks! Tony > -----Original Message----- > From: Han Zhou <hz...@ovn.org> > Sent: Thursday, July 30, 2020 7:19 PM > To: Tony Liu <tonyliu0...@hotmail.com> > Cc: Numan Siddique <nusid...@redhat.com>; Han Zhou <hz...@ovn.org>; ovs- > dev <ovs-...@openvswitch.org>; ovs-discuss <ovs-discuss@openvswitch.org> > Subject: Re: [ovs-discuss] [OVN] DB backup and restore > > > > On Thu, Jul 30, 2020 at 7:04 PM Tony Liu <tonyliu0...@hotmail.com > <mailto:tonyliu0...@hotmail.com> > wrote: > > > Hi, > > > > Just update, finally make this snapshot/rollback work for me. > > The rollback is not live though. Here is what I did. > > > > 1. Make a snapshot by ovsdb-client. Assuming no ongoing > > Transactions, and data is consistent on all nodes. The > > Snapshot can be done on any node. It doesn't include any > > cluster info. That's probably why the man page says this is > > for standalone and A/B only. But that cluster info seems > > not required to restore. > > > > 2. To rollback/restore, stop services on all nodes, starting > > from followers to the leader. > > > > 3. Pick a node as the new leader, copy snapshot to be the DB > > file. Then start the service. A cluster with new cluster ID > > will be created. The node will be allocated a new server ID > > as well. > > > > 4. On the rest two nodes, remove the DB file, restart service > > with remote-address pointing to the leader. > > > > Now, the new cluster starts working with the rollback data. > > > The steps you gave may work, but it is weird. It is better to just > follow the steps mentioned in this section: > > https://github.com/openvswitch/ovs/blob/master/Documentation/ref/ovsdb.7 > .rst#backing-up-and-restoring-a-database > > > > > > > "ovs-client restore" doesn't work for me, not sure why. > > ==== > > ovsdb-client: ovsdb error: /dev/stdin: cannot identify file type > > ==== > > I tried to restore the snapshot created by backup, also the > > Directly copied DB file, neither of them works. Wondering anyone > > experienced such issue? > > > > Maybe your command was wrong. Could you share your command line, and the > version used? > > > > > > To Numan, it would great if you could share the details to use > > Neutron-ovn-sync-util. > > > > > > Thanks! > > > > Tony > > > > From: Tony Liu <mailto:tonyliu0...@hotmail.com> > Sent: Thursday, July 30, 2020 4:51 PM > To: Numan Siddique <mailto:nusid...@redhat.com> ; Han Zhou > <mailto:hz...@ovn.org> > Cc: Han Zhou <mailto:hz...@ovn.org> ; ovs-dev <mailto:ovs- > d...@openvswitch.org> ; ovs-discuss <mailto:ovs-discuss@openvswitch.org> > Subject: Re: [ovs-dev] [ovs-discuss] [OVN] DB backup and restore > > > > Hi Numan, > > I found this comment you made a few years back. > > - At neutron-server startup, OVN ML2 driver syncs the neutron > DB and OVN DB if sync mode is set to repair. > - Admin can run the "neutron-ovn-db-sync-util" to sync the DBs. > > Could you share the details to try those two options? > > > Thanks! > > Tony > > From: Tony Liu<mailto:tonyliu0...@hotmail.com> > Sent: Thursday, July 30, 2020 4:38 PM > To: Han Zhou<mailto:hz...@ovn.org> > Cc: Han Zhou<mailto:hz...@ovn.org>; ovs-dev<mailto:ovs- > d...@openvswitch.org>; ovs-discuss<mailto:ovs-discuss@openvswitch.org> > Subject: Re: [ovs-dev] [ovs-discuss] [OVN] DB backup and restore > > Hi, > > I have another thought after some diggings. Since I am with > OpenStack, all networking configurations are from OpenStack. > I could snapshot OpenStack MariaDB, restore and run > neutron-ovn-db-sync to update OVN DB. Would that be a cleaner > solution? > > BTW, I got this error when restore the OVN DB. > ovsdb-client: ovsdb error: /dev/stdin: cannot identify file type > > The file was created by "backup" command. > > > Thanks! > > Tony > > From: Tony Liu<mailto:tonyliu0...@hotmail.com> > Sent: Thursday, July 30, 2020 3:41 PM > To: Han Zhou<mailto:hz...@ovn.org> > Cc: Han Zhou<mailto:hz...@ovn.org>; ovs-dev<mailto:ovs- > d...@openvswitch.org>; ovs-discuss<mailto:ovs-discuss@openvswitch.org> > Subject: Re: [ovs-dev] [ovs-discuss] [OVN] DB backup and restore > > Hi, > > A quick question here. Given this man page. > http://www.openvswitch.org/support/dist-docs/ovsdb-client.1.txt > > It says backup and restore commands are for OVSDB standalone and > > active-backup databases. > > > > Can they be used for RAFT cluster? If not, what would be the > concern, > > like inconsistency? > > > > If I restore to a follower, is the request going to be forwarded to > the > > leader to restore DB for the whole cluster? But I believe it's > recommended > > to restore to the leader directly for performance sake. > > > > I am going to give it a try anyways, see how it works. Will make > sure > > there is no configuration update from OpenStack side while running > such > > snapshot and restore process. > > > > > > Thanks! > > > > Tony > > From: Han Zhou<mailto:hz...@ovn.org> > Sent: Thursday, July 30, 2020 12:23 PM > To: Tony Liu<mailto:tonyliu0...@hotmail.com> > Cc: Han Zhou<mailto:hz...@ovn.org>; ovs-discuss<mailto:ovs- > disc...@openvswitch.org>; ovs-dev<mailto:ovs-...@openvswitch.org> > Subject: Re: [ovs-discuss] [OVN] DB backup and restore > > > > On Thu, Jul 30, 2020 at 10:56 AM Tony Liu <tonyliu0...@hotmail.com > <mailto:tonyliu0...@hotmail.com> <mailto:tonyliu0...@hotmail.com > <mailto:tonyliu0...@hotmail.com> >> wrote: > Hi Han, > > That doc helps. I will run some tests and update here. The use case > I want > to cover is snapshot/rollback and backup/restore. > > ======== > Actually, "at-least-once" consistency, because OVSDB does not have > a session > mechanism to drop duplicate transactions if a connection drops > after the server > commits it but before the client receives the result. > ======== > I saw duplicated datapath bindings for the same logical switch once, > if you > recall. This may explain that. The ovn-northd connection to sb-db > is dropped > before receiving the result. So ovn-northd initiates another > transaction to > create datapath binding for the same logical switch. > > Yes, this is a possibility. > However, in reality, this is usually not a problem: > > 1) If DB schema has table keys properly defined, the redundant > transaction from clients would be rejected by DB server because of key > constraint check. In the datapath binding case, this doesn't work > because of the poor definition of the datapath_binding table. It should > have had "logical_switch_router" column defined and set as a key (in > addition to the "tunnel_key") instead of storing it in external_ids. The > duplicated entries would have been avoided. The other tables such as > port_binding would never have such problem. > > 2) OVSDB clients usually monitors and syncs all (interested) data > from server to local, so when they do declarative processing, they could > correct problems by themselves. In fact, ovn-northd does the check and > deletes duplicated datapaths. I did a simple test and it did cleanup by > itself: > 2020-07-30T18:55:53.057Z|00006|ovn_northd|INFO|ovn-northd lock > acquired. This ovn-northd instance is now active. > 2020-07-30T19:02:10.465Z|00007|ovn_northd|INFO|deleting > Datapath_Binding abef9503-445e-4a52-ae88-4c826cbad9d6 with duplicate > external-ids:logical-switch/router ee80c38b-2016-4cbc-9437-f73e3a59369e > > I am not sure why in your case north was stuck, but I agree there > must be something wrong. Please collect northd logs if you encounter > this again so we can dig further. > > I see two ways to improve it. > 1) On client side, if the connection is broken while waiting for > the result > of a transaction, the client checks the transaction state, > committed or not, > when it reconnects to the leader (maybe a different node). > Do we have such check today? > > Clients does check. In this case when transaction was actually > successful but appears to be failed from client point of view, the check > doesn't help. > > 2) I see client connection is dropped by the leader when it's busy. > I don't > think this is a good way to control the traffic. The server can > cache and > hold the request when it's busy, or even push back. Dropping > connection > is not a good option. Any thoughts here? > > The server doesn't make this kind of decisions. It could be simply > overloaded and disconnected from the cluster, or even worse, a node > could crash after commiting the transaction. > > Thanks, > Han > > > Thanks! > > Tony > > From: Han Zhou<mailto:hz...@ovn.org> > Sent: Wednesday, July 29, 2020 11:38 PM > To: Tony Liu<mailto:tonyliu0...@hotmail.com> > Cc: ovs-discuss<mailto:ovs-discuss@openvswitch.org>; ovs- > dev<mailto:ovs-...@openvswitch.org> > Subject: Re: [ovs-discuss] [OVN] DB backup and restore > > > > On Wed, Jul 29, 2020 at 10:58 PM Tony Liu <tonyliu0...@hotmail.com > <mailto:tonyliu0...@hotmail.com> <mailto:tonyliu0...@hotmail.com > <mailto:tonyliu0...@hotmail.com> >> wrote: > > > > Hi, > > > > > > > > There is any guidance to backup and restore OVN nb-db and sb-db? > > > > > > > > Is /var/lib/openvswitch/ovn-[ns]b/ovn[ns]b.db the only database > file? > > > > > > > > For 3-node DB cluster, is replication 3 (the data is replicated > onto > > > > All 3 nodes)? > > > > > > > > Are DB files on 3 nodes identical? > > > > > > > > If I stop a DB follower and empty the DB file on the follower > node, > > > > when I start it back, is the whole DB going to be replicated to > it? > > > > > > > > To backup the DB, is it OK to copy the DB file from any node, > assuming > > > > no transaction ongoing? > > > > > > > > Is the following going to work to restore the DB? > > > > * Stop all 3 DBs. > > > > * Copy backup DB file to one node, empty DB file on the rest two > nodes. > > > > * Bootstrap the node with DB file. > > > > * Start the rest two nodes to join the cluster. > > > > For ovsdb operations, please refer to "man 7 ovsdb", or here: > https://github.com/openvswitch/ovs/blob/master/Documentation/ref/ovsdb.7 > .rst > <https://github.com/openvswitch/ovs/blob/master/Documentation/ref/ovsdb. > 7.rst> > > > > > > > Do I need to restore sb-db as well? Or restore nb-db only and let > > > > ovn-northd to sync data from nb-db to sb-db. Chassis data should > be > > > > updated by onv-controller? > > > > You don't have to restore sb-db. ovn-northd and ovn-controllers > will sync the data in SB DB. > However, it may take quite some time to sync if the scale is large. > Also, remember that the mac_binding table in SB will not be > restored by ovn-controller because it is populated as a result of ARP > packets handling by ovn-controller. The entries will be generated again > only if new ARP packets are observed by ovn-controller. > > > > > > > I am running scaling test. It takes quite a lot of time to build > > > > Configurations. Wondering if I can back and restore DB to > rollback > > > > to some checkpoint to avoid restart all over. > > > > > > > > > > > > Thanks! > > > > > > > > Tony > > > > > > > > _______________________________________________ > > discuss mailing list > > disc...@openvswitch.org <mailto:disc...@openvswitch.org> > <mailto:disc...@openvswitch.org <mailto:disc...@openvswitch.org> > > > https://mail.openvswitch.org/mailman/listinfo/ovs-discuss > > > _______________________________________________ > dev mailing list > d...@openvswitch.org <mailto:d...@openvswitch.org> > https://mail.openvswitch.org/mailman/listinfo/ovs-dev > > _______________________________________________ > dev mailing list > d...@openvswitch.org <mailto:d...@openvswitch.org> > https://mail.openvswitch.org/mailman/listinfo/ovs-dev > > _______________________________________________ > dev mailing list > d...@openvswitch.org <mailto:d...@openvswitch.org> > https://mail.openvswitch.org/mailman/listinfo/ovs-dev > > _______________________________________________ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
