Once you have configured DRBD and have an active DRBD device and file system, you can configure MySQL to use the chosen device to store the MySQL data.
When performing a new installation of MySQL, you can either select to install MySQL entirely onto the DRBD device, or just configure the data directory to be located on the new file system.
In either case, the files and installation must take place on the primary node, because that is the only DRBD node on which you can mount the DRBD device file system as read/write.
You should store the following files and information on your DRBD device:
MySQL data files, including the binary log, and InnoDB data files.
MySQL configuration file (
To set up MySQL to use your new DRBD device and file system:
If you are migrating an existing MySQL installation, stop MySQL:
shell> mysqladmin shutdown
my.cnf onto the DRBD device. If
you are not already using a configuration file, copy one of
the sample configuration files from the MySQL distribution.
root-shell> mkdir /mnt/drbd/mysql root-shell> cp /etc/my.cnf /mnt/drbd/mysql
Copy your MySQL data directory to the DRBD device and mounted file system.
root-shell> cp -R /var/lib/mysql /drbd/mysql/data
Edit the configuration file to reflect the change of directory
by setting the value of the
datadir option. If you have
not already enabled the binary log, also set the value of the
datadir = /drbd/mysql/data log-bin = mysql-bin
Create a symbolic link from
to the new configuration file on the DRBD device file system.
root-shell> ln -s /drbd/mysql/my.cnf /etc/my.cnf
Now start MySQL and check that the data that you copied to the DRBD device file system is present.
root-shell> /etc/init.d/mysql start
Your MySQL data should now be located on the file system running on your DRBD device. The data will be physically stored on the underlying device that you configured for the DRBD device. Meanwhile, the content of your MySQL databases will be copied to the secondary DRBD node.
Note that you cannot access the information on your secondary node, as a DRBD device working in secondary mode is not available for use.