Already configured Master-Slave Replication among two different machines. Now the problem is that it only allows the Master to enter the data and Slave to view this. the changes which made in Slave is not reflected in master.
My question is that is it possible to create a full duplex replication among two MySQL servers. ie, If i change the data either in master or in Slave both will reflected in both the machines.
References:
MySQL Master-Slave Replication
Steps to configure Master-Slave Replication
Yes, but there are risks, because replications is asynchronous. That is, both servers could insert the same row, and then when they process the replication log from the other server, they get a conflict.
You can listen to more about this problem in this free webinar: The Hazards of Multi-writing in a Dual-Master Setup
You should consider using a cluster solution with synchronous replication, like Percona XtraDB Cluster.
Related
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.
I have a MySQL Replication setup up and running:
Database A (Server 1 as master) --> Database A (Server Z, acting as the slave)
I now want to use the same Slave Server (Z) to be a slave of two other databases; totally different databases (e.g. B and C), not other copies if Database A.
I've followed this simple guide:
https://www.digitalocean.com/community/tutorials/how-to-set-up-master-slave-replication-in-mysql
But when it comes to adding the second database to the slave server in /etc/my.cnf, I don't see how it's possible to have more than one profile.
Basically I am thinking I need both of these blocks in my.cnf on the slave server but it won't be that simple, right?
log_error="/var/log/mysql/error.log"
server-id=2
log_bin="/var/log/mysql/mysql-bin.log"
binlog_do_db=database_a
log_error="/var/log/mysql/error.log"
server-id=3
log_bin="/var/log/mysql/mysql-bin.log"
binlog_do_db=database_b
Is it possible, or do I literally need a new slave server for each unique database I want to replicate?
Is it possible to, on the slave server, have specific conf files for each database, e.g. /etc/databasea.cnf and /etc/databaseb.cnf so I can specify different settings for each database?
Thanks in advance
Multi-source replication is only available in MySQL starting with 5.7.6 or MariaDB starting with 10.0.1.
Multi-Source Replication enables a replication slave to receive transactions from multiple sources simultaneously. Multi-source replication can be used to back up multiple servers to a single server, to merge table shards, and consolidate data from multiple servers to a single server. Multi-source replication does not implement any conflict detection or resolution when applying the transactions, and those tasks are left to the application if required. In a multi-source replication topology, a slave creates a replication channel for each master that it should receive transactions from.
Source:
MySQL : http://dev.mysql.com/doc/refman/5.7/en/replication-multi-source.html
MariaDB: https://mariadb.com/kb/en/mariadb/multi-source-replication/
For my application I will have one master db with one slave db, the slave will be used for me to run my backups on without interrupting my application. However I have seen examples with one master with multiple slaves and I am wondering why and if my application would benefit from having more than one slave that I have not thought of.
So put simply, what could be the reasons for having more than one slave?
Multiple slaves allows you to distribute your reads. If you have a read heavy application, you can scale it with multiple slave servers. It also offers a layer of fault tolerance - if your master dies, you can promote one of the slaves to be the master.
I'm kind of lost there, I want to setup a common MASTER/SLAVE replication on a MariaDB database. I choose MASTER/SLAVE over MASTER/MASTER to avoid complexifying things. The SLAVE will be used only if the MASTER server is down.
I've setup MariaDB 10.0.x, but when I start reading on how to achieve this replication, they introduce Galera, which, if I understand correctly, replaces MariaDB.
What do you use to tell the SLAVE server to take the relay if the MASTER server is down ? Is it handled automatically via the Galera Cluster ?
If possible, I don't want my application to be aware of the slave server : I just want to configure it with the IP of MariaDB MASTER, and if it can't be reached, to use the SLAVE instead. (But I do not want to specify this fallback in the application level)
Thanks
What you are looking for can be achieved. I just completed a setup of MariaDB 10 using asynchronous replication (not Galera). To ensure maximum uptime I setup master / master replication and used mysql-mmm to monitor the setup. This tool will manage a virtual IP and point it at one of the two masters for writing purposes. This ensures consistent writes against a single master as to avoid corruption of the data. If one master fails the virtual IP will be mapped to the other master. This provides the high availability aspect. The instructions stated below were very clear and easy to follow.
http://mysql-mmm.org/mmm2:guide
Good luck!