Re: [ovs-discuss] OVN: ovn-sbctl backoff
Appreciate it! You connected dots for me. Tony From: Han Zhou Sent: July 23, 2020 05:10 PM To: Tony Liu Cc: Han Zhou ; ovs-discuss Subject: Re: [ovs-discuss] OVN: ovn-sbctl backoff On Thu, Jul 23, 2020 at 4:34 PM mailto:tonyliu0...@hotmail.com>> wrote: > > Good to know! I recall I read somewhere saying only the leader takes write > request. I will double check! > > Well, in that case, I have another question, why is such leader role > required? In a quorum based cluster, all nodes are equal. And why does > ovn-northd have to connect to the leader? > Guess I will need to read more about RAFT:) > Quick answer: only leader node does the actual write, aso all writes are redirected to leader, but it can be initiated from followers. ovn-northd connects to leader for better performance because it heavily writes. The manpage does provide more details, and yes RAFT paper has even more. > > Thanks! > > Tony > > On Jul 23, 2020 4:26 PM, Han Zhou mailto:hz...@ovn.org>> wrote: > > > > On Thu, Jul 23, 2020 at 4:07 PM > mailto:tonyliu0...@hotmail.com>> wrote: > > > > Thanks Han for the prompt responses! > > That option is ok for reading. If I want to write, I have to connect to the > > leader, right? Then my question remains, how does ovn-sbctl find out how to > > connect to the leader? > > > > RAFT doesn't require you to connect to leader for writing. You can connect to > any node and write. > However, if for any reason you want to connect to the leader, you need to > specify the DB connection method as: ,,...,. For > example: > tcp:10.0.0.2:6641<http://10.0.0.2:6641>,tcp:10.0.0.3:6641<http://10.0.0.3:6641>,tcp:10.0.0.4:6641<http://10.0.0.4:6641>. > You can read more details about OVSDB clustering in manpage ovsdb(7). > > Thanks, > Han > > > Thanks again! > > > > Tony > > > > On Jul 23, 2020 3:57 PM, Han Zhou mailto:hz...@ovn.org>> > > wrote: > > > > > > > > On Thu, Jul 23, 2020 at 3:43 PM Tony Liu > > mailto:tonyliu0...@hotmail.com>> wrote: > > > > > > Hi, > > > > > > In case of ovsdb cluster, when I run ovn-sbctl, it connects to the unix > > > socket of local sb-db. > > > If local sb-db is not the leader, ovn-sbctl tries another server to look > > > for the leader. > > > How does ovn-sbctl connect to another server? By which connection? > > > How does ovn-sbctl know the connection? > > > Or the local sb-db asks to be the leader to respond ovn-sbctl? > > > I can't figure out how it works from verbose messages. > > > Any help to clarify is appreciated! > > > > > > > > > Thanks! > > > > > > Tony > > > > If you don't intentionally try to connect to the leader, you can use > > ovn-sbctl --no-leader-only ... to avoid the retry. > > If you want to avoid typing this option every time, you can export > > OVN_SBCTL_OPTIONS"="--no-leader-only", and then just run ovn-sbctl ... > > (does this answer your question?) > > > > Thanks, > > Han > > > > > > ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
Re: [ovs-discuss] OVN: ovn-sbctl backoff
On Thu, Jul 23, 2020 at 4:34 PM wrote: > > Good to know! I recall I read somewhere saying only the leader takes write request. I will double check! > > Well, in that case, I have another question, why is such leader role required? In a quorum based cluster, all nodes are equal. And why does ovn-northd have to connect to the leader? > Guess I will need to read more about RAFT:) > Quick answer: only leader node does the actual write, aso all writes are redirected to leader, but it can be initiated from followers. ovn-northd connects to leader for better performance because it heavily writes. The manpage does provide more details, and yes RAFT paper has even more. > > Thanks! > > Tony > > On Jul 23, 2020 4:26 PM, Han Zhou wrote: > > > > On Thu, Jul 23, 2020 at 4:07 PM wrote: > > > > Thanks Han for the prompt responses! > > That option is ok for reading. If I want to write, I have to connect to the leader, right? Then my question remains, how does ovn-sbctl find out how to connect to the leader? > > > > RAFT doesn't require you to connect to leader for writing. You can connect to any node and write. > However, if for any reason you want to connect to the leader, you need to specify the DB connection method as: ,,...,. For example: tcp:10.0.0.2:6641,tcp:10.0.0.3:6641,tcp:10.0.0.4:6641. > You can read more details about OVSDB clustering in manpage ovsdb(7). > > Thanks, > Han > > > Thanks again! > > > > Tony > > > > On Jul 23, 2020 3:57 PM, Han Zhou wrote: > > > > > > > > On Thu, Jul 23, 2020 at 3:43 PM Tony Liu wrote: > > > > > > Hi, > > > > > > In case of ovsdb cluster, when I run ovn-sbctl, it connects to the unix socket of local sb-db. > > > If local sb-db is not the leader, ovn-sbctl tries another server to look for the leader. > > > How does ovn-sbctl connect to another server? By which connection? > > > How does ovn-sbctl know the connection? > > > Or the local sb-db asks to be the leader to respond ovn-sbctl? > > > I can't figure out how it works from verbose messages. > > > Any help to clarify is appreciated! > > > > > > > > > Thanks! > > > > > > Tony > > > > If you don't intentionally try to connect to the leader, you can use ovn-sbctl --no-leader-only ... to avoid the retry. > > If you want to avoid typing this option every time, you can export OVN_SBCTL_OPTIONS"="--no-leader-only", and then just run ovn-sbctl ... > > (does this answer your question?) > > > > Thanks, > > Han > > > > > > ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
Re: [ovs-discuss] OVN: ovn-sbctl backoff
Good to know! I recall I read somewhere saying only the leader takes write request. I will double check!Well, in that case, I have another question, why is such leader role required? In a quorum based cluster, all nodes are equal. And why does ovn-northd have to connect to the leader?Guess I will need to read more about RAFT:)Thanks!TonyOn Jul 23, 2020 4:26 PM, Han Zhou wrote:On Thu, Jul 23, 2020 at 4:07 PMwrote:>> Thanks Han for the prompt responses!> That option is ok for reading. If I want to write, I have to connect to the leader, right? Then my question remains, how does ovn-sbctl find out how to connect to the leader?>RAFT doesn't require you to connect to leader for writing. You can connect to any node and write.However, if for any reason you want to connect to the leader, you need to specify the DB connection method as: ,,...,. For example: tcp:10.0.0.2:6641,tcp:10.0.0.3:6641,tcp:10.0.0.4:6641.You can read more details about OVSDB clustering in manpage ovsdb(7).Thanks,Han> Thanks again!>> Tony>> On Jul 23, 2020 3:57 PM, Han Zhou wrote: On Thu, Jul 23, 2020 at 3:43 PM Tony Liu wrote:> >> > Hi,> >> > In case of ovsdb cluster, when I run ovn-sbctl, it connects to the unix socket of local sb-db.> > If local sb-db is not the leader, ovn-sbctl tries another server to look for the leader.> > How does ovn-sbctl connect to another server? By which connection?> > How does ovn-sbctl know the connection?> > Or the local sb-db asks to be the leader to respond ovn-sbctl?> > I can't figure out how it works from verbose messages.> > Any help to clarify is appreciated!> >> >> > Thanks!> >> > Tony>> If you don't intentionally try to connect to the leader, you can use ovn-sbctl --no-leader-only ... to avoid the retry.> If you want to avoid typing this option every time, you can export OVN_SBCTL_OPTIONS"="--no-leader-only", and then just run ovn-sbctl ...> (does this answer your question?)>> Thanks,> Han>> ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
Re: [ovs-discuss] OVN: ovn-sbctl backoff
On Thu, Jul 23, 2020 at 4:07 PM wrote: > > Thanks Han for the prompt responses! > That option is ok for reading. If I want to write, I have to connect to the leader, right? Then my question remains, how does ovn-sbctl find out how to connect to the leader? > RAFT doesn't require you to connect to leader for writing. You can connect to any node and write. However, if for any reason you want to connect to the leader, you need to specify the DB connection method as: ,,...,. For example: tcp:10.0.0.2:6641,tcp:10.0.0.3:6641,tcp:10.0.0.4:6641. You can read more details about OVSDB clustering in manpage ovsdb(7). Thanks, Han > Thanks again! > > Tony > > On Jul 23, 2020 3:57 PM, Han Zhou wrote: > > > > On Thu, Jul 23, 2020 at 3:43 PM Tony Liu wrote: > > > > Hi, > > > > In case of ovsdb cluster, when I run ovn-sbctl, it connects to the unix socket of local sb-db. > > If local sb-db is not the leader, ovn-sbctl tries another server to look for the leader. > > How does ovn-sbctl connect to another server? By which connection? > > How does ovn-sbctl know the connection? > > Or the local sb-db asks to be the leader to respond ovn-sbctl? > > I can't figure out how it works from verbose messages. > > Any help to clarify is appreciated! > > > > > > Thanks! > > > > Tony > > If you don't intentionally try to connect to the leader, you can use ovn-sbctl --no-leader-only ... to avoid the retry. > If you want to avoid typing this option every time, you can export OVN_SBCTL_OPTIONS"="--no-leader-only", and then just run ovn-sbctl ... > (does this answer your question?) > > Thanks, > Han > > ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
Re: [ovs-discuss] OVN: ovn-sbctl backoff
Thanks Han for the prompt responses!That option is ok for reading. If I want to write, I have to connect to the leader, right? Then my question remains, how does ovn-sbctl find out how to connect to the leader?Thanks again!TonyOn Jul 23, 2020 3:57 PM, Han Zhou wrote:On Thu, Jul 23, 2020 at 3:43 PM Tony Liuwrote:>> Hi,>> In case of ovsdb cluster, when I run ovn-sbctl, it connects to the unix socket of local sb-db.> If local sb-db is not the leader, ovn-sbctl tries another server to look for the leader.> How does ovn-sbctl connect to another server? By which connection?> How does ovn-sbctl know the connection?> Or the local sb-db asks to be the leader to respond ovn-sbctl?> I can't figure out how it works from verbose messages.> Any help to clarify is appreciated!>>> Thanks!>> TonyIf you don't intentionally try to connect to the leader, you can use ovn-sbctl --no-leader-only ... to avoid the retry.If you want to avoid typing this option every time, you can export OVN_SBCTL_OPTIONS"="--no-leader-only", and then just run ovn-sbctl ...(does this answer your question?)Thanks,Han ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
Re: [ovs-discuss] OVN: ovn-sbctl backoff
On Thu, Jul 23, 2020 at 3:43 PM Tony Liu wrote: > > Hi, > > In case of ovsdb cluster, when I run ovn-sbctl, it connects to the unix socket of local sb-db. > If local sb-db is not the leader, ovn-sbctl tries another server to look for the leader. > How does ovn-sbctl connect to another server? By which connection? > How does ovn-sbctl know the connection? > Or the local sb-db asks to be the leader to respond ovn-sbctl? > I can't figure out how it works from verbose messages. > Any help to clarify is appreciated! > > > Thanks! > > Tony If you don't intentionally try to connect to the leader, you can use ovn-sbctl --no-leader-only ... to avoid the retry. If you want to avoid typing this option every time, you can export OVN_SBCTL_OPTIONS"="--no-leader-only", and then just run ovn-sbctl ... (does this answer your question?) Thanks, Han ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
[ovs-discuss] OVN: ovn-sbctl backoff
Hi, In case of ovsdb cluster, when I run ovn-sbctl, it connects to the unix socket of local sb-db. If local sb-db is not the leader, ovn-sbctl tries another server to look for the leader. How does ovn-sbctl connect to another server? By which connection? How does ovn-sbctl know the connection? Or the local sb-db asks to be the leader to respond ovn-sbctl? I can't figure out how it works from verbose messages. Any help to clarify is appreciated! Thanks! Tony ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss