[ovs-dev] ovsdb active backup deployment

[Andy Zhou]

On Wed, Aug 17, 2016 at 8:30 AM, Numan Siddique <nusiddiq at redhat.com> wrote:

> ​Hi Andy,
> I have started working on integrating ovsdb-server HA support with
> pacemaker (via OCF heartbeat, i.e ocf:heartbeat).
>

Thanks for working on it.

>
> Few comments below.
>
>
>
>>
>> >>> Thanks for helping out.
>> >>>
>> >>> Given that, I now plan to work from bottom up, initially focusing on
>> >>> ovsdb server changes.
>> >>>
>> >>> 1. Add a state in ovsdb-server for it to know whether it is an active
>> >>> server.  Backup server will not accept any connections.  Server
>> started with
>> >>> --sync-from argument will be put in the back state by default.
>> >>>
>> >>> 2. Add appctl commands to allow manually switch state.
>> >>>
>>
>
> In order to write the ocf script for ovsdb-server, we need a mechanism to
>  - know if the ovsdb-server instance is running as master or slave
>
 Current 2.6 branch code does not have this feature. You can always use
switch commands to
force the state.   On the other hand, adding an appctl command seems
appropriate and can be
useful for trouble shooting as well.  I will work it.

 - to switch the state of the ovsdb-server to either master or slave.
>
These are currently supported via appctl commands:
ovsdb-server/connect-active-ovsdb-server
ovsdb-server/disconnect-active-ovsdb-server

 ​
> The initial (very dirty, not working properly) ocf script  can be found
> here - [1]
>
> I know you have already mentioned about adding this support above. This is
> just a confirmation that it would be consumed by the pacemaker ocf script
> once available.
>
> [1] - https://github.com/numansiddique/resource-agents/commit/
> 7f6c4d8977c7cf525ec22793d8adf5b308bc431e
>
>
> ​Thanks
> Numan
> ​
>
> >>> 3. Add a new table for backup server to register its address and ports.
>> >>> OVSDB clients can learn about them at run time. Back up server should
>> issue
>> >>> an
>> >>> transaction to register its address before issuing the monitoring
>> >>> request.  This feature is not strictly necessary, and can be pushed
>> to HA
>> >>> manager,
>> >>> but having it built into ovsdb-server may make it simpler for
>> >>> integrationl.
>> >>>
>> >>> What do you think?
>> >>>
>> >>>
>> >>>
>> >> 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.
>>
>> >
>> >
>>
>> >
>> > --
>> > Russell Bryant
>> >
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>>
>
>