We have successfully set up a Master-Slave replication as described in MySQL literature.
However, I'm curious if anyone has set up a bidirectional replication. For example, if one has a Drupal or Wordpress installation. The first ('master') database server goes down, and the secondary ('slave') picks up. All the while, users continue to make edits, writing new data. When the First database server is restarted, can changes written to the Second be replicated upward to the First?
That is: are there other replication strategies than only the Master-Slave?
You can do Master-Master replication. Unfortunately, Neither Drupal or Wordpress support this. The best thing to do is Master-Slave or Master-Slave-Slave, then make the first slave in the chain the new Master if the original master goes down. Then reconfigure the old Master to slave off the new Master (or last slave in the chain).
How often does your mysql server go down?
Master-Master Replication has some disadvantages. For example data inconsistencies can easily occur.
Have you tried synchronous multi-Master Replication with Galera Cluster for MySQL?
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Weird question I know. I have a master MySQL database which I'm not allowed to touch and need to build a slave for. I would like the slave to be as real time (as possible) of a replica of the master and would like the slave to be HA.
Does MySQL (or MariaDB) replication work when run on a cluster, say, can I make a Galera cluster and make it replicate from a master out of the box or must I use binlog-esque tools?
For the curious; this new slave cluster will be on a different network and will have many large, important queries made against it regularly - the aim of the game is to reduce load on the master and reduce network traffic.
If you are not planning on doing modifications to the downstream slave server, then you can just set up multiple slave servers. This way if one of the slaves goes down you can use another one. This will place a small load on the master for each added slave but whether this added load is even measurable depends on your setup.
Galera could work but I believe you would have to reconfigure one of the nodes to act as the slave if the current one goes down. This would place a minimal load on the master but it would require a manual intervention whenever the current "slave" node goes down.
Parallel replication should also help speed up replication for MariaDB servers.
I have two mariadb servers one is configured as master and the other as a replica of this master. I have created a database named params on master and it has a table with a couple of items in it.
How can I see this table and access or modify it using the mysql shell on the replica?
Is this even possible or I have miss understood the replication altogether?
Check that replication works
If you aren't seeing the database on the slave replica, it would be good to check that the output of SHOW SLAVE STATUS doesn't return any errors. A good resource for getting started with replication is the MariaDB KB article on the subject.
When you have confirmed that replication works, you can connect to the slave replica and you should see the database there.
How replication works in MariaDB
Replication in MariaDB will propagate all changes that happen on the master server to any slave servers that are replicating from it. This allows you to read the same data from multiple places without burdening the master server. It does not allow you to seamlessly share data across multiple servers (a Galera cluster offers some of this).
The downside of master-slave replication is that when you want to make a change, you have to make it on the master in order to keep the data consistent across all servers. The benefit of it is the higher availability of your data and increased throughput of read queries. The Replication Overview article has a more detailed description of what replication is and lists some use cases for it.
Surprisingly I can't find anything on the internet which speaks to this. We currently have a master slave slave mysql set up. We are considering making a move to mysql cluster, for scalability reasons. It would be really nice if we could make the cluster a slave of the current master and run a dev environment off the cluster for now. Even better would be if we could do a master master relationship between the current master and the cluster.
Our concern is that our data has to be kept very current, so not being able to do this replication would mean downtime. If this replication is not possible, what is the smoothest possible way to make the transition. We're currently running mariaDB.
I read some article about how to implement high-availability solution,the use Heartbeat to check the master mysql is broken,if it broken then switch to the backup server,
one question is when the master server broken,the backup server work on ,how the backup server get the master server 's pre-data
another question is maybe sometimes the master server is not broken,but the mysql service is broken,in this situation is Heartbeat still will switch to the backup server?
What you usually want to do is setup a master-master configuration, but generally only use one master. That was each master also acts as a slave to the other master. In theory, you can modify records in either one and they will keep in sync. In practice, I wouldn't do heavy updates on both servers at once.
My current setup is a master-master configuration, with each master also having a slave off of it. Then you can "failover" to the secondary master/slave and "fail back" when needed. I actually do this if I have database modifications that will take a while.
Basically I want to setup a replication server for mysql datbase. I am completely new to this concept and appreciate any help pointing me in the right direction.
If at all the slave goes down, will it effect the master in anyway?
Thanks.
No, it will not affect the master if the slave goes down. The Slaves connect to the master and request the changes.
If you intend on having 2 servers replicated, then you can use Master-Master replication. This means that either one of the database servers can go down without loss of data or access. This is extremely resilient to failure however you can get duplicate key errors on fast successive inserts, like using MySQL to handle sessions. This can be solved programatically through.
The downside of the Master-Slave set up is that if the master fails you have to manually assign another Master, fix the failed master and then bring back into the group. Otherwise failure of any or all Slaves will not affect the Master.