[Kea-users] Fail-over

Jan Schermer jan at schermer.cz
Tue Apr 26 19:53:35 UTC 2016


I deployed a PoC kea cluster to achieve HA

at the backend are 3 mysql servers in a galera cluster
on each node runs kea that uses the localhost mysql instance as a backend

this way everything is synchronized

it's not the cleanest solution but it works and it should not break evein in split-brain scenarios, in theory :-)

I need a 3-way high-availabilty cluster for DHCP and this was the only solution I could think of, all the other solutions were either even more hack-ish or limited to master/slave (and you can't do true HA with just 2 nodes...)

Jan


> On 26 Apr 2016, at 21:42, Jonis Maurin Ceara <jonis at fearp.usp.br> wrote:
> 
> For us, is a matter of availability. We have all of our servers in two different phisical sites and sometimes, we need to shutdown for maintenance or update these sites (one at a time) and we need services to  keep running for users......that why we need services running in more than one servers without 'manual switching' between then.
> 
> Our MySQL is running in both machine and using syncronous data sync. For external clients, there is two floating IP's that are allocated on both servers and balanced using DNS. If one server fails, both floating IP's are allocated in one machine (the running one) and clients still with connection.
> 
> 
> Jonis Maurin Ceará
> Analista de Sistemas
> FEA-RP
> Help Desk +55 (16) 3315-3898
> Audiovisual +55 (16) 3315-3927
> Desenv. Sistemas +55 (16) 3315-4485
> Infraestrutura +55 (16) 3315-8539 / 0672
> Atendimento Web: http://suporte.fearp.usp.br <http://suporte.fearp.usp.br/>
> 
> De: "Thomas Andersen" <than at itu.dk <mailto:than at itu.dk>>
> Para: "Wlodek Wencel" <wlodek at isc.org <mailto:wlodek at isc.org>>
> Cc: kea-users at lists.isc.org <mailto:kea-users at lists.isc.org>
> Enviadas: Terça-feira, 26 de Abril de 2016 16:27:15
> Assunto: Re: [Kea-users] Fail-over
> 
> The reason for dual dhcp server is not a matter of availability for me. The old dhcp server has been running for about 4 years rock solid. But dual server allow me to ease the upcoming updates one server at a time.
> /Thomas 
> Sent from my Cyanogen phone
> Den 26/04/2016 21.03 skrev Wlodek Wencel <wlodek at isc.org <mailto:wlodek at isc.org>>:
> Hello,
> it good to hear that someone is using kea in such way and it's working!
> Internally we just started to test such solution. It's not strict
> failover protocol but high availability should be secured but we want
> make sure.
> 
> If time allows us we will publish white paper "How to setup failover in
> kea using db backend".
> 
> Regards,
> Włodek Wencel
> ISC QA engineer.
> 
> On 04/26/2016 08:17 PM, Thomas Andersen wrote:
> > I have 2 kea with mysql lease. They are both connecting to the same
> > mysqlserver though. Not local mysql.
> > 
> > Exact same config file from a local Github instance.
> > 
> > Br
> > Thomas
> > 
> > Sent from my Cyanogen phone
> > 
> > Den 26/04/2016 20.04 skrev Jonis Maurin Ceara <jonis at fearp.usp.br <mailto:jonis at fearp.usp.br>>:
> > 
> >     Hi again :)
> > 
> >     I read that there's no specific function or option to make an DHCP
> >     master/slave in Kea.....but it's possible to make 2 servers with
> >     SAME configurations (subnet, options, etc...) and both using SAME
> >     lease and host configuration database? This could cause any problem
> >     or is ok to use?
> > 
> >     This is what I'm thinking:
> > 
> >     Server-A - MySQL and KEA (always started)
> >     |
> >     |
> >     |
> >     Master/Master MySQL replication between both servers
> >     |
> >     |
> >     |
> >     Server B - MySQL and KEA (always started)
> > 
> > 
> > 
> >     Jonis Maurin Ceará
> >     Analista de Sistemas
> >     FEA-RP
> >     Help Desk +55 (16) 3315-3898
> >     Audiovisual +55 (16) 3315-3927
> >     Desenv. Sistemas +55 (16) 3315-4485
> >     Infraestrutura +55 (16) 3315-8539 / 0672
> >     Atendimento Web: http://suporte.fearp.usp.br <http://suporte.fearp.usp.br/>
> > 
> > 
> > 
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> > 
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