Mysql – GFS2 as shared storage for MySQL cluster with active active setting

clusteringconfigurationMySQLmysql-5.7

I am using MySQL 5.7 on RHEL 7.1. For cluster management I am using Pacemaker and corosync. For shared storage, I am using GFS2 file system with iSCSI server

I am trying to implement MySQL active-active cluster (both nodes running at the same time). I have two nodes with MySQL server running. I am not able to give same data directory (shared storage) for both the nodes.

I tried to change the data directory in my.cnf file. After that the service didn't start. Currently, I am using the default storage engine i.e. InnoDB storage engine.

Is this a problem of the underlying storage engine or something else we need to change in the configuration?

Best Answer

Two instances of mysqld must not use the same data files. The code is not designed to handle unexpected changes to the file, which will happen by the other instance.

(I assume you are talking about Master-Master replication when you say "cluster"?)

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MySQL Cluster — Storing table data on data nodes

everything is in order!

The data nodes don't have individual files for each table and so you won't see the table names there. What you're seeing with the MySQL Server directories is not the files containing the contents of the tables but a copy of the data dictionary/schema definitions for those tables (e.g. if you add more rows to these tables then the files you see with the data nodes should increase in size but the ones with the MySQL Servers should not).

Regards, Andrew.

Mysql – Setting up MySQL Cluster on Two Systems

Your management configuration seems fine to me. It sounds like ndb_mgmd didn't quite die or there is a problem with the contents in the /var/lib/mysql-cluster directory on the management server.

You might also want to make sure that ndb_mgmd isn't starting automatically, like through some startup script in /etc/init.d/.

To try and resolve the issue, I'd start with these steps first.

Since you are just getting started and don't have any real data yet.

Kill any left over ndb_mgmd processes with: killall ndb_mgmd or by rebooting if killall doesn't help.
Completely delete everything within /var/lib/mysql-cluster: rm -Rf /var/lib/mysql-cluster/*
Start the cluster process again: ndb_mgmd -f /etc/config.ini --initial
Verify that ndb_mgmd is listening with netstat

$> netstat -tlpn

Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:1186 0.0.0.0:* LISTEN 3251/ndb_mgmd

Connect to management node

$> ndb_mgm
ndb_mgm> show
Connected to Management Server at: localhost:1186
Cluster Configuration


[ndb_mgmd(MGM)] 1 node(s)
id=1    @192.168.9.26  (mysql-5.1.61 ndb-7.1.22)

Update

Here is a Quick Start guide from Oracle with all nodes, management, mysql and data running on one server.

http://downloads.mysql.com/tutorials/cluster/GetMySQLClusterRunning-LINUX.pdf

Best Answer

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MySQL Cluster — Storing table data on data nodes

Mysql – Setting up MySQL Cluster on Two Systems

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