----- On 14 Nov, 2015, at 2:24 PM, Li Junhong
lijh...@gmail.com wrote:
> Hi All,
>
> I'm new to galera these days. I setup my 3 nodes galera cluster by setting
> the my.cnf like this in those 3 nodes:
>
> wsrep_cluster_name=MyCluster
> wsrep_cluster_address="gcomm://
192.168.1.80,192.168.1.85,192.168.1.86"
> # set this all all 3 nodes
> wsrep_node_name=galera.node1
> wsrep_node_address="192.168.1.80" # this is for the 1st node,
> "192.168.1.85" for the 2nd node, and "192.168.1.86" for the 3rd node
>
> Then started up the first node by "service mysql bootstrap", and joined
> 2nd/3rd node by "service mysql start"
>
> Now the cluster is working fine. When I check the "show status like
> 'wsrep%';" in mysql, it showed that "wsrep_cluster_status=Primary" in all 3
> nodes, which confused me a bit.
>
>| wsrep_cluster_size | 3
> |
>| wsrep_cluster_state_uuid | c563be0f-89df-11e5-9b69-46f65bd61f3e
> |
>| wsrep_cluster_status | Primary
> |
>| wsrep_ready | ON
> |
>
>
> My questions are:
> 1) Is this (all 3 nodes showing wsrep_cluster_status=Primary)
Look up what primary actually mean:
http://galeracluster.com/documentation-webpages/index.html
> what we call > multi-master mode of galera?
stop making assumptions.
There is no multi-master mode of galera. Galera doesn't care which node you write too.
> 2) In my current cluster, if I shutdown the 1st started node, I assume it
> is the real master(which is started by "service mysql bootstrap"), what
> happens to the left two nodes? Is the master role transferred to one of the
> left 2 nodes in this case?
try and see.
> I find that when I want to bring the 1st node
> back to the cluster, I just needed to run "service mysql start" instead of
> "service mysql bootstrap", is that a correct process?
yes. See documentation as to what bootstrap actually means.
> 3) I am planning to manage the galera cluster with pacemaker+corosync with
> pcs command, is there galera pacemaker agent recommended for multi-master
> mode? I found one in
https://github.com/ClusterLabs/resource-agents.git ,
> but it seems for master/slave mode, actually, that leads to my above
> confusions subsequently.
read about the agent:
https://github.com/ClusterLabs/resource-agents/blob/master/heartbeat/galera#L32
Colocate the appropriate resources (IP/LB config etc.) related to what pacemaker considers the master node(s) and use those to write to those nodes.
> I googled a lot about my above questions, didn't get clear answers, which I
> wish to get here. Thank you guys.
Googling just wastes your time. Find the official docs, read them, think and then apply and validate.
--
--
Daniel Black, Engineer @ Open Query (
http://openquery.com.au)
Remote expertise & maintenance for MySQL/MariaDB server environments.