What will be the best practice to deploy Gallera cluster having two physical servers (Server A and Server B).
first Option
Galera Arbitrator (Where it should be configured in A or B or in any
other system)
Can i have like one DB node 1 in server A and the other two DB nodes 2,3 in Server B.
Will the cluster works if the server B goes down with both node 2,3 unavailable.
"Best" is to have three different locations for 3 physical servers. (One could be garbd.)
If you put two nodes (regular and/or garbd) in the same physical location, you are vulnerable to earthquake, hurricane, flood, etc.
Related
How do i setup multiple mariadb server in one single VM using Galera Cluster?
If configuration links are available please share me?
I have searched in galera website its says add the nodes into cluster and not the adding the multiple mariadb server into cluster
Analysis of having 3 Galera nodes in a single server,
All 3 in a single VM
One in each of 3 VMs
No VMs
Notes:
Galera provides crash protection -- if a node goes down due to hardware failure, the other nodes continue serving the database needs. Not so with all of them sharing the same server and disk(s).
By having multiple instances of MySQL (whether as Galera nodes or not), you can make better use of CPUs. But, since MySQL rarely needs all of the available CPU, I see no advantage in this configuration.
Each instance uses some RAM for static things -- 3 instances leads to 3 copies of such. Other things (eg, caches) scale with RAM size.
No advantage in networking.
(There may be other reasons why there is virtually no difference between a single instance and multiple instances.)
Currently I have 2 data centers and mariaDB master-master semi-sync replication will be employed to synchronize data between 2 sites.
In order to improve local availability, we are planned to deploy one more mariaDB in each site to form a master-slave replication. i.e. Cross-site replication is master-master replication, while local replication is master-slave replication
I would like to know if this topology makes sense and technically feasible to do.
Can mariaDB support mixed-mode of replication at the same time?
No you can't have partial asynchronous master slave and semi-sync on the same server.
I recommend moving to either Galera (3 sites recommended to alleviate split brain or devise an alternative resolution);
Or multi-master all-(server)-to-all-(other-servers) replication (without log-slave-updates).
A Master can have any number of Slaves; those slaves can be either local to the Master's datacenter, or remote. One of those "Slaves" can be another Master, thereby giving you "dual-Maser".
For Dual-Master, I recommend writing to only one of them (until a failover).
These are partial HA solutions:
* Replication
* Dual-Master
* Semi-sync
* Using only 2 datacenters
Galera (and soon, Group Replication) are better than any combination of the above. But for good HA, you need 3 geographically separate datacenters (think flood, tornados, etc)
I am not familiar with a restriction against async + semi-sync on the same server.
Be aware that every Slave must perform every write operation, so a Slave is not necessarily less busy than a Master. However, having more than one server for "reads" does spread out the read load.
For Galera, 3 nodes is recommended. 4 or 5 is OK; more than 5 may stress the network and the handshaking needed. Galera allows any number of Slaves hanging off each 'node'.
I'm running into an issue with the way Galera cluster is set up to work with MariaDB.
Each node in the cluster has to have a configuration that houses the IP addresses of every other node (inclusive) in the cluster. If I ever want to add a node to the cluster, I have to manually add that node's IP address to the configurations on every other node.
This makes spinning up and down servers dynamically for the cluster difficult.
Are there any work arounds for this? Possibly a way to notify every node of a new node being added to the cluster remotely?
Galera clusters only need one server working as a master node. You can use any or all of the servers in the cluster as the cluster address for the new node and the new node will automatically connect to the rest of the nodes.
Example
Active Cluster:
10.0.0.2 (the first node of the galera cluster)
10.0.0.3
10.0.0.4
If we want to add 10.0.0.5 to the cluster, we can use any of the following as a cluster address for it:
gcomm://10.0.0.2
gcomm://10.0.0.3
gcomm://10.0.0.4
gcomm://10.0.0.2,10.0.0.3
gcomm://10.0.0.2,10.0.0.4
gcomm://10.0.0.3,10.0.0.4
gcomm://10.0.0.2,10.0.0.3,10.0.0.4
The down side to this is that the new node would lose the other servers as fall back if the ones that they have configured in their cluster address are down.
So a work around for this is to have X number of static nodes that will never go down, then use all of those as the cluster addresses for any new slaves that you bring up.
I would like to synchronize only some databases on a cluster, with replicate-do-db.
→ If I use the Galera cluster, are all data sent over the network, or are nodes smart enough to only fetch their specific databases?
On "classic" master/slave MariaDB replication, filters are made by the slave, causing network charge for nothing if you don't replicate that database. You have to configure a blackhole proxy to filter binary logs to avoid this (setup example), but the administration after is not really easy. So it would be perfect with a cluster if I can perform the same thing :)
binlog_... are performed in the sending (Master) node.
replicate_... are performed in the receiving (Slave) node.
Is this filtered server part of the cluster? If so, you are destroying much of the beauty of Galera.
On the other hand, if this is a Slave hanging off one of the Galera nodes and the Slave does not participate in the "cluster", this is a reasonable architecture.
Suppose that we have two application servers(app1 and app2) and also we setup multi master MariaDB clustering with two nodes(node1 and node2) without any HAProxy.Can we connect app1 to node1 and app2 to node2 and also both of app1 and app2 write to node1 and node2?
Does it cause any conflict?
Galera solves most of the problems that occur with Master-Master:
If one of Master-Master dies, now what? Galera recovers from any of its 3 nodes failing.
If you INSERT the same UNIQUE key value in more than one Master, M-M hangs; Galera complains to the last client to COMMIT.
If a node dies and recovers, the data is automatically repaired.
You can add a node without manually doing the dump, etc.
etc.
However, there are a few things that need to be done differently to when using Galera: Tips