How to Change a MySQL Data Directory to a New Location Using a Symlink

How to Change a MySQL Data Directory to a New Location Using a Symlink


Databases grow over time, sometimes outgrowing the space on the file system. You can also run into I/O contention when they’re located on the same partition as the rest of the operating system. RAID, network block storage, and other devices can offer redundancy and other desirable features. Whether you’re adding more space, evaluating ways to optimize performance, or looking to take advantage of other storage features, this tutorial will guide you through relocating MySQL’s data directory.

The directions here are suitable for servers that run a single instance of MySQL. If you have multiple instances, the guide How To Move a MySQL Data Directory to a New Location on Ubuntu 16.04 can help you with directions for explicitly changing the location through configuration settings.


To complete this guide, you will need:

In this example, we’re moving the data to a block storage device mounted at /mnt/volume-nyc1-01. You can learn how to set one up in the How To Use Block Storage on DigitalOcean guide.

No matter what underlying storage you use, this guide can help you move the data directory to a new location.

Step 1 — Moving the MySQL Data Directory

To ensure the integrity of the data, we’ll shut down MySQL:

  1. sudo systemctl stop mysql

systemctl doesn’t display the outcome of all service management commands, so if you want to be sure you’ve succeeded, use the following command:

  1. sudo systemctl status mysql

You can be sure it’s shut down if the final line of the output tells you the server is stopped:

. . . Jul 18 11:24:20 ubuntu-512mb-nyc1-01 systemd[1]: Stopped MySQL Community Server.

With the server shut down, we’ll move the existing database directory to the new location:

  1. sudo mv /var/lib/mysql /mnt/volume-nyc1-01/mysql

Next, we’ll create the symbolic link:

  1. sudo ln -s /mnt/volume-nyc1-01/mysql /var/lib/mysql

With the symlink in place, this seems like the right time to bring up MySQL again, but there’s one more thing to configure before we can do that successfully.

Step 2 — Configuring AppArmor Access Control Rules

When you move the MySQL directory to a different file system than the MySQL server, you will need to create an AppArmor alias.

To add the alias, edit the AppArmor alias file:

  1. sudo nano /etc/apparmor.d/tunables/alias

At the bottom of the file, add the following alias rule:

. . .
[label /etc/apparmor.d/tunables/alias]
alias /var/lib/mysql/ -> /mnt/volume-nyc1-01/mysql/,
. . .

For the changes to take effect, restart AppArmor:

  1. sudo systemctl restart apparmor

Note: If you skipped the AppArmor configuration step and tried to start mysql, you would run into the following error message:

Job for mysql.service failed because the control process exited with error code. See "systemctl status mysql.service" and "journalctl -xe" for details.

The output from both systemctl and journalctl concludes with:

Jul 18 11:03:24 ubuntu-512mb-nyc1-01 systemd[1]: mysql.service: Main process exited, code=exited, status=1/FAILURE

Since the messages don’t make an explicit connection between AppArmor and the data directory, this error can take some time to figure out. However, a look at the syslog will show the problem:

  1. sudo tail /var/log/syslog
Nov 24 00:03:40 digitalocean kernel: [ 437.735748] audit: type=1400 audit(1479945820.037:20): apparmor="DENIED" operation="mknod" profile="/usr/sbin/mysqld" name="/mnt/volume-nyc1-01/mysql/mysql.lower-test" pid=4228 comm="mysqld" requested_mask="c" denied_mask="c" fsuid=112 ouid=112

Now we’re ready to start MySQL.

  1. sudo systemctl start mysql
  2. sudo systemctl status mysql

Once you’ve restarted MySQL, take the opportunity to ensure that your data is in order and that MySQL is functioning as expected.


In this tutorial, we’ve moved MySQL’s data and used a symlink to make MySQL aware of the new location. We’ve also updated Ubuntu’s AppArmor ACLs to accommodate the adjustment. Although we were using a Block Storage device, the instructions here should be suitable for redefining the location of the data directory regardless of the underlying technology.

This approach is only suitable if you are running a single instance of MySQL. If you need to support multiple MySQL instances running on a single server, How To Move a MySQL Data Directory to a New Location on Ubuntu 16.04 can help you.

Thanks for learning with the DigitalOcean Community. Check out our offerings for compute, storage, networking, and managed databases.

Learn more about our products

About the authors

Still looking for an answer?

Ask a questionSearch for more help

Was this helpful?

This textbox defaults to using Markdown to format your answer.

You can type !ref in this text area to quickly search our full set of tutorials, documentation & marketplace offerings and insert the link!

This comment has been deleted

    Not going to lie. I figured out how to make the mysql data folder onto another disk just today. I just mounted the disk under /var/lib/mysql and it seems to have done the trick. I added the information to the /etc/fstab file and now the disk will be mounted every time. I thought about doing a link to a MySQL Dump but I did not know the full impact of what was going on at the time.

    I’ve done something like this by mount bind, and I think there is no need to do additional AppArmor config in this case.

    Try DigitalOcean for free

    Click below to sign up and get $200 of credit to try our products over 60 days!

    Sign up

    Join the Tech Talk
    Success! Thank you! Please check your email for further details.

    Please complete your information!

    Featured on Community

    Get our biweekly newsletter

    Sign up for Infrastructure as a Newsletter.

    Hollie's Hub for Good

    Working on improving health and education, reducing inequality, and spurring economic growth? We'd like to help.

    Become a contributor

    Get paid to write technical tutorials and select a tech-focused charity to receive a matching donation.

    Welcome to the developer cloud

    DigitalOcean makes it simple to launch in the cloud and scale up as you grow — whether you're running one virtual machine or ten thousand.

    Learn more
    DigitalOcean Cloud Control Panel