Re: [codership-team] is pc.ignore_quorum=yes right solution for 3+2 cluster?

[alexey.y...@galeracluster.com]

You want a miracle. Miracles don't happen.

Basically there can be two approaches:

1) designated arbitrator. No arbitrator - no service.
2) quorum. No quorum - no service.

By default Galera implements 2). You can configure it to work like 1) by
setting weights of all nodes but one to 0. But it is probably not what
you want. What you want is 3 (three) datacenters.

Any pc.ignore_... option is a recipe for disaster.

On 2015-03-26 17:49, zbi...@o2.pl wrote:
> Hello,
>
> Have this:
> MariaDB-Galera-server.x86_64 10.0.17-1.el7.centos
> galera.x86_64 25.3.9-1.rhel7.el7.centos
>
> 'main location': db1 db3 db5
> 'backup location': db2 db4
>
> ha proxy serves one IP for web application and connects to all nodes
> db1-5
>
> If 'main location' is gone 'backup location' is alone and blocked
> because
> of lack of quorum: 2/5 present, required 3/5 to be active.
>
> *How to make 'backup location' alone active and usable when 'main
> location'
> is gone?*
>
> Tried:
> pc.ignore_sb=yes -> 'backup location' alone still
> lockspc.ignore_sb=yes pc.ignore_quorum=yes
> -> 'backup location' unlocked and active but have 2 single nodes
> instead of
> 2 node cluster. Split brain occures.
> pc.ignore_sb=no pc.ignore_quorum=yes -> 'backup location' unlocked and
> active, no split brain so far, but do not feel it is done correctly.
> Maybe
> because started db2 as first server in cluster and that is why it
> works?
>
> Maybe it would be better to restore pc.ignore_sb=no pc.ignore_quorum=no
> and
> use pc.weight?
>
>
> 'main location': db1 db3 db5 <- pc.weight = 1 for all here 1+1+1=3
> 'backup location': db2 db4 <- pc.weight = 2 for all here 2+2=4
>
> Is it correct 3+4? What is better pc.ignore_ or pc.weight= 3+4?
>
> How to configure to make it working when all 4/5 servers will be gone
> so
> the last one will be still active and available to application?